yack

to throw up, usually after drinking

I drank too much tonight, I just yacked behind his shed

yack

in referance the Lil Jon & The East Side Boyz song "Da Blow" where the hook states "the blow, the pills, the yack, the herb". The term "yack" is actually referring to cognac (pronounced: "cone-yack"). So in essence the song is referring to the blow (cocaine), the pills (ecstacy and/or pharmacutical), the yack (cognac), the herb (marijuana). Which covers all the most common methods of getting fucked up.
In less urban environments, the term is more commonly used to describe the act of vomiting.
noun: yack means congac
verb: yack means to vomit

Da blow, da pills, da yack, da herb... (repeat)
or
I drank too much, I think I'm gonna yack.

yack

verb. Meaning to throw up or vomit.

I am going to yack on your sweater.

yack

Abbreviation of Cognac - i.e. expensive Brandy. Alcoholic beverage

me and my brothers sipping yack

yack

cocaine, blow, powder, snow, gack

let's get yacked out tonight man.

yack

To be ridiculously wet shooting the basketball; used in same context as "swish" or "splash." Can also be used in other context, such as a long killstreak in Modern Warfare 2, and combined with other words to form fantastic contractions.

Here's Bryant, for three...YACK.

I was yackin' on some bitches in M-Dub Deuces last night.

Combinations: yackadaisical, yack in the box, Yackensack, yackity-yack don't talk back, yack my bitch up, etc.

yack

when a bitch ass nigga throws up

you see that pussy ass freshman over there just yacked after ripping my fucking juul