Rob Gronkowski‘s gonna need a few showers after his Fanatics Fest appearance on Thursday … ’cause his buddy Tom Brady dunked him in a tank full of Raising Cane’s sauce!!

The wild moment happened at the popular chicken giant’s Fan Zone event … where a bunch of fans crowded around the GOAT to watch him plunge his former favorite target into 500 gallons of signature sauce.

It turns out Brady had one more highlight in him … as he threw a perfect spiral at the target, sending Gronk into a dunk tank filled to the brim with the delicious condiment.

Sauce went flying as the 6’6″, 265-pound future Hall of Famer plummeted down … and even though it’s great on chicken fingers, Gronk wasn’t the biggest fan of having it in every nook and cranny of his buff bod.

He was a good sport about it, though … and even posed for a pic with Brady and Cane’s founder Todd Graves after the dunk.