I arrived home from work and...........

my girlfriend started punching and kicking me.
"How could you?!" she screamed. "How f*cking could you?! You've fucked my sister you b*stard!"
"I'm sorry," I confessed. "I got to work and she was lying there...naked. I'm only human. What was I supposed to do?"
"The f*cking autopsy," she cried.

thats SICK, but still FUNNY.