look up any word, like dirty sanchez:
 
2.
if you dont know what someone is talking about then this comes in handy.
hey whats the answer to this problem

fuck if i know
by mike October 07, 2003
 
1.
When you have no idea what someone is asking you you should reply with this
girl: what time do you get off work?
guy: Fuck if I know
by OG March 31, 2004