look up any word, like donkey punch:
 
1.
not bloody likely
"I hooked up with Bongo last week at her barbecue."
"You, with her? Fat chance!"
by Harley February 05, 2004
364 62
 
2.
Actual meaning: a very good chance, opposite of a slim chance.

Typical usage: sarcasticly, as to imply that there is no chance in hell.
Let's do the right thing and serve these guys!

Pschh. Fat chance. (chuckles)
by TreeWeezel October 24, 2011
49 14
 
3.
The opportunity to have sex with a overweight individual.
That heifer over there is giving you the eye, now's your fat chance.
by nucleus May 31, 2004
48 257