Top definition
An event, action, or result that is hard for a human of normal thought to process.
That bitch cheated on me, with my best friend? Unmothafuckinbelievable.

or.

Unmothafuckinbelievable, my son can't be gay.
by jamaal.a.manic April 30, 2009
Get the mug
Get a unmothafuckinbelievable mug for your mom Beatrix.