look up any word, like blumpkin:
 
1.
A unattractive person, time, or thing.
Lupe is guack without her make- up
by BigKali k July 22, 2010
 
2.
When someone is constantly nagging or yelling at you non-stop over the most little things and least worried and mattered problems in the world, yet they would constantly make a big deal out of it by nagging and yelling the living daylights out of you.
My mom is going to GUACK the hell out of me because I miss a millimeter spot on a plate when I was doing the dishes.

My wife kept guacking at me because I was half a second late home for dinner.
by Yang Out w/ my Wang Out March 17, 2008
 
3.
A guido that is being whack
Can also be used like:
Guackin
Guacka
"Yo man, stop bein guack"
"Did you see that guacka over there?"
"Stop guackin, yo"
by guack March 17, 2008
 
4.
Short for guacamole. Currency. Money. Cash. Referring to the green ink used on most U.S. currency bills.
You gonna need some guack to date that girl!
by RentMan January 28, 2009