Is an abbreviation for: I'll/I'd Fuck Anything or.. I'll/I'd Fuck Anyone (if you're a little less adventurous)
Although usually said in it's abbreviated form, sometimes spoken fully.
Meaning you would mount and have sex with literally anything living or non.
Often used as a nonsensical response when you have nothing else to say, lack interest in a conversation or sometimes used to scare others out of conversation so they'll go away.
Example 1:
Person1: What girls are you into?
Person2: IFA
Example 2:
Person1: You're up against the best player tonight
Person2: IFA
Example 3:
Person1: What's up?
Person2: I'll fuck anything
7👍 4👎