Diddy -- Hits the Stage ... Then His Ass

You can't keep Diddy down ... even when he falls into a giant hole.

It happened Sunday night during an epic Bad Boys Records tribute at the BET Awards featuring Mase, Faith Evans, Lil' Kim, and 112 ... Diddy danced over what appeared to be an elevator lift opening. He fell smack on his ass ... hard.

But the football father took it like a champ -- popping right up and finishing to a standing ovation.

Now that's what you call strength and conditioning.

Diddy seemed in good shape when he hit up BOA after the show, but wasn't into our questions about his UCLA football fight.