From the words fucking and mistake, the word fistake means when a guy/girl has sexual intercourse with another guy/girl when they are drunk. The next morning when they realize who they just slept with they realize the just made a fistake.
Kelsey was drunk and fucked Nate, in the morning when she came to it, she realized how big of a fistake she had just made.
by imadeafistake March 30, 2010