― W. Somerset Maugham, The Razor's Edge
My definition of 'wisecrack' defines it as "a remark intended as a clever joke, especially one which criticizes someone."
The word dates from 1924, sardonically superimposing 'wise' with the mid-15th century Scottish word for 'boast' ... as in, "not what it's cracked up to be." The word 'crackers' for southerners came from an 18th century, pre-revolution speech by G. Cochrane, of whom I could find no information online apart from his quip:
"I should explain to your Lordship what is meant by 'crackers' ... a name they have got from being great boasters; they are a lawless set of rascalls [sic] on the frontiers of Virginia, Maryland, the Carolinas and Georgia, who often change their places of abode."
The term became synonomous with poor white trash by the 19th century, so that by the 20th the combination "wise-crack" could be used as a word for "cheap shot." Which is what they are.
Wisecracks are fun. You're only allowed a second or two to get them off for effect, and there's a certain smug charm in having the wit to concoct them and shoot them off with the right tone and volume to really hit home. Some of the proudest moments of my life come from totally destroying some really annoying prof or political pundit with a masterful cutdown, simply because I hated that bastard or what they stood for so much.
I haven't thrown out every wisecrack as a message of hate; most of them are a moment of humour inserted into some circumstance that was somewhat boring or perhaps condescending. One place I worked at told us that in order for us to feel 'engaged' in the company's activities, they were going to give us a survey to fill out - but that we shouldn't worry, since it was only going to be ten question. To which I said, good and loud for everyone to hear, "Gee, I don't know if I can feel engaged with only ten questions."
No, I was not fired. But it did interject a moment of humor into an otherwise dull and somewhat annoying procedural event. Such interjections accomplish one task: derail the speaker and diminish the importance of what's being said.
Sometimes a wisecrack includes a pun, such as remarking that to restore a magic item's illumination charges requires a cure light wands spell or that it really takes six to make a proper wolf pack. Such lines get a healthy 'BOO' or groan from the crowds, and another moment of self-importance is happily achieved.
There is a particular kind of personality who is especially given to making wisecracks prodigiously. It is almost always someone with the kind of snappy wit needed, though not always. A young person is more likely to be someone who makes the attempt and fails, than someone who is older and almost always hits the mark to some degree. Many people try to do it, since there seems to be a sort of cultural notariety to be gained ... Jim always has something funny to say; he's great to have at a party. Some women have the gift and it makes them wildly attractive to some men ... and so other women give it a whirl and turn out to just be hateful. Film, theatre, criticism, journalism and so on have all done well with the wisecrack, with some personality based entirely upon their perceived ability to do it well (though its often rehearsed). A wisecracking 'personality' can just as easily become typecast and their career destroyed ... but only because the audience wants more of what they were famous for, and the more rapid-fire the better.
However ... the ordinary at home wisecracker has another personality characteristic that should not be overlooked where it comes to D&D campaigns: they are in it for the immediate gratification.
A great many potential D&D campaigns have been destroyed by the proliferation of wisecracking. Note the earlier statement about derailing the speaker. In D&D, it is presumed that the speaker is not your boss or some corporate flunky; not a politician whose political views make you squirm; not a tight-assed bitch on the train and not a self-important fuckwit giving you orders. It is somewhat presumed that you're actually there to listen to the DM, because you want to play the game and what he or she has to say is important.
Then why is it that wisecracking is so thoroughly part of the gaming table?
There's no question that it's an aggressive response; S. Maugham considered it so aggressive as to lump it in with the rack and the stake. It exists to cut down, undermine, parody and humiliate the speaker. For that purpose, I'm right in there with the retort designed to slap down opponents.
But in the game, it has no place.
Naturally, there are DMs who do nothing but wisecrack their way through a session. That is the 'session' to them - who can think of the smartest thing, or the most smart things to say in the least amount of time, so that the game becomes a one-upmanship contest until everyone has had a thorough and satisfying evening. That is, if you like this sort of thing.
If you are a noobie DM, however, or if you're on a quest to create honest drama in your campaign, the wisecrack is worse than repeated, random cold showers. Just as you attempt to lift the party into a state of concern or anxiety, someone makes a joke about the recent magic item that's been picked up, and the tension is gone. You describe the massive gate in front of the castle, with its terrifying head - that you've spent an hour working on the description for - and someone compares it to Barney the purple dinosaur and the tension is gone. Someone has to roll a die to keep from falling into the Pit of Neverfound, and there's a shout of "USE THE FORCE LUKE" before the die is rolled and the tension is gone.
There's a conflict here, between those at your table who are seeking the aforementioned immediate gratification, and those who are seeking something long term. Long term takes time; it takes effort; it requires concentration, and it requires that a person step out of their comfort zone in order to truly embrace the fantasy of what is going on.
That's the thing about the wisecracker. Whoever they are, they DON'T want to step out of themselves. The whole point of wisecracking is to hold up a sign which says, "Pay attention to me!" It is a handwaving, dancing, fuck you signal that forces people to turn their minds from whatever the hell is going on and point it straight at the present wit. It is selfish, it is abusive, it is calculated to pump one's own importance. It is NOT designed for D&D.
What can you do about it?
Almost nothing, short of asking the person to be respectful ... which they probably won't, since the insistence on wisecracking is based on being disrespectful. The greater the demand for respect, the more tempting it is to throw in a remark. The greater the tension of the moment, the greater the emotional and verbal response to a really smart crack, and thus the greater the temptation to do it. However you may try to explain it to the wisecracker, they are caught in a loop. They KNOW this could be possibly the best remark EVER, given that just about everyone in the room is freaked out to the nth degree. How can they resist.
You could threaten to drop a -1,000 x.p. bomb on anyone who makes a wisecrack ... but the problem is that often wisecracks ARE funny, and you tend to look like an asshole if you punish someone who's just made everyone at the table laugh. Everyone is here to have fun, after all, and fun is synonymous with laughter, so ipso facto, why are you fucking Jim just 'cause he's funny?
But if you've been running long enough, you've had this experience: Jim had to work, and couldn't play. And Jim's friend, who is the person who especially finds Jim the funniest person ever, can't come because his mother needs someone to help her move boxes for some purpose or other. Which just leaves Maggie, Dave and Garrett to play.
And holy shit, you just had the best fucking running you've ever, ever had. The tension was so thick you could build igloos from it. At one point, Dave's involvement was so high he broke the pencil he was holding - and no one laughed when that happened.
For that one night, you really felt like a DM. You really felt you had your finger on the pulse of the players, and you really felt you were all right in the game.