Rob Gronkowski — Smashes Football Cake On Bro’s Head … At Epic Vegas Party!!

The Rob Gronkowski have fun trains rolls on … there were hot chicks (a lot of them), bottles of champagnes, a Lombardi Trophy shaped cake … and TMZ Sports has the EPIC have fun video.

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 pot, danced on stage, and showered the crowded with bubbly.

Best part … Gronk SPIKING the football cake … on his brothers head!

Check out the video.