Someone always making feeble wisecracks, who laughs at his/her own jokes and is generally deserving of severe and painful punishment.
That guy is up there thinking we are all listening to his puerile crap, such a wisenheimer.
Someone who makes smart aleck, sarcastic comments, often at inappropriate times and usually at someone else's expense.
"Don't smart off to your mother, you little wisenheimer."
a wise ass, generally a nebbish male trying to get over with a humorous, but usually feeble attempt to make someone else the butt of the joke. Wisenhemiers are usually called out and decsribed as such.
youz a f'in wisenheimer and you're gonna end up wit yer dick in yer mouth.