Pretty sure this is a SpongeBob reference. In the episode where spongebob eats a pie, towards the end he screams "Gary, you're gonna eat you're food, AND YOU'RE GONNA LIKE IT!". If you don't believe me, ask Lotus. She usually does Spongebob references with Regular Show drawings.
Rigby: Mordecai, if you actually did yell that right in front of her she would of ran away crying like she did after she told you she couldn't be your permanet girlfreind and she would never marry you.
Mordecai: ha ha I know, we were just exploding for fun
Rigby: oh, heh, maybe I could go for it.
Benson: NO YOU WERE SUPPOSED TO EXPLODE INTO A MILLION PEICES BECAUSE THE PIE YOU ATE WAS A BOMB
Mordecai: OH YEAH *pulls out pie* you mean this pie, I never ate it. but don't worry I'm sure it won't blow me up when I eat it.
Rigby: if you die, I'm gonna have an extreme heart attack and die right after.
Mordecai: HAH don't worry about it dude, the pies fine.
Mordecai: yeah, it's fine, it's fine, it's fine it's fine,
Rigby: HAHAHA your right they were just born to mess with your head.
Mordecai: *hmp hmp* well, one bite won't hurt *eats it* ah, so good
Rigby: AAAAAAAAAAAHH DX (wakes up in bed) oh, it was only a night mare X3