Kanye & Will Smith -- Drake Is Sooo Funny (VIDEO)

Drake didn't only kill Meek Mill onstage at OVO Fest ... he burned him backstage too -- sharing a HUGE laugh with Kanye West and Will Smith.

Rumor is ... the superstars went all LMFAO over a meme Drake used to mock his rival. Check out the video ... it's hard to make out what's on Will's iPhone screen, but THEY think it's hysterical.

What is 100% clear -- Will looks really tight with Toronto's favorite son! Damn, Meek.

So much for, "In West Philadelphia born and raised ..."