12:11 PM PT -- Drake did his best Rob Gronkowski impression at the Raptors' parade -- catching a full beer that a fan threw his way ... and chugging the hell out of it!!!

Drizzy has been raging on Kawhi Leonard's double-decker parade bus all morning long ... and when someone tossed a brew his way -- he went full Stone Cold Steve Austin on it!!!

He cracked it open ... poured it down the hatch -- and appeared to dab afterward!!

The parade is going on hour No. 5 ... but there's a chance we haven't seen the best from Drake yet -- he's supposed to address the crowd once the parade reaches the end.

... getchya popcorn ready!!

Sorry, Kawhi Leonard, it might be the Raptors' championship parade day ... but all eyes will be on Drake ... 'cause everyone wants to know -- how crazy will Drizzy get!?!

Toronto shockingly upset the Warriors in six games last week ... and the Canadian city is throwing a party to celebrate -- and we'll be live streaming the whole thing.

Kawhi, Kyle Lowry and Nick Nurse will all be there ... but the man we all wanna see is the 6 God -- 'cause he's been front and center of everything during this Raptors' run.

Will there be more Golden State trash talk? Some more coaching shoulder rubs? Maybe even another new rap song?!?