The Patriots superstar hit up Surrender Nightclub at the Encore hotel in Vegas last night ... and did what Gronk does -- got super turnt up and smashed stuff!!!
Sources at the club tell us Gronk arrived around 1AM ... pounded champagne straight from the bottle, danced on stage, and showered the crowded with bubbly.
Best part ... Gronk SPIKING the football cake ... on his brothers head!
Check out the video.