Tom Brady Shows Off Retirement Bod In Underwear Selfie

Tom Brady clearly ain't letting himself go in retirement ... the former quarterback just shared a selfie in nothing but his undies -- and he looks GOOOOOOOD!!!!

TB12 posted the pic early Monday morning on his Twitter page ... paying off a bet he made with his clothing company way back in June.

At the time, he said he'd recreate models wearing his Brady brand underwear if the tweet got 40,000 likes. When the co. reminded him of it all Monday, he paid it off in a big way ... and we're all grateful for it.

Tom showed off some biceps, some pecs, and a set of abs -- all while his hand was conveniently placed to cover up his junk.

He mentioned Julian Edelman and Rob Gronkowski while revealing the pic -- asking the two, who have posed often in their undies for various brands in their lifetimes, if he was doing it right.

Of course, Tom's bod shouldn't exactly surprise anybody -- while he's a retired man now, it's only been a couple weeks since he left football.