Amy Schumer Reportedly Flashed Boob at Jimmy Buffett's Memorial

Amy Schumer knows how to perk up a room ... playing a prank at Jimmy Buffett’s memorial to ease the melancholy in the room -- all by pulling her top down!

The actress/comedian was honored at the Variety Power of Women event in NYC where Sascha Seinfeld -- the daughter of Jerry Seinfeld and a writer on AS’ show “Life & Beth” -- introduced her by telling the NSFW story, Page Six reports.

The way Seinfeld tells it ... Amy attended a memorial dinner for the late great singer -- who passed away last September. Jimmy's widow Jane Buffett came in the room and Amy went to greet her, after making one small change to her outfit.

Sascha says Amy pulled one of her breasts out and ran over to hug Jane ... apparently cracking up everyone in the room and lightening the mood a bit.

BTW ... Sascha also lifted the lid on a more serious Amy too -- one she says she greatly admires and respects. Check out the clip of her talking to hear it for yourself.

Amy and Jimmy were pretty close before the rockstar passed ... he even made a guest appearance during the second season of "Life & Beth," and she's previously talked about her closeness with JB.

Jimmy passed last year after a battle with skin cancer ... the rockstar's been celebrated in many different ways -- including a singalong featuring some of the biggest singers and actors in the world. He was 76.