Kim Kardashian was the butt of a lot of jokes at a roast that was supposed to be all about Tom Brady -- with a not-so-welcome reception too ... but, in fairness, she took it in stride.

The reality star was one of many of celebs on hand Sunday night for Netflix's "The Greatest Roast of All Time: Tom Brady" -- and when she was eventually introduced by Kevin Hart and co. to come up to the podium to say a few words ... people didn't seem happy to see her.

The clip's going viral ... a cascade of boos greeted Kim when she got onstage and started her monologue -- which was taking aim at Kevin ... but she couldn't even get the words out.

Eventually, KK had to stop because the boos were so damn loud and drowning her out at the microphone -- and she shot the crowd a look, basically telegraphing ... "Really, y'all?" Somebody offstage (sounds like it might've been Jeff Ross) told everyone to settle down.

That wasn't the end of it for Kim, BTW ... she was put into the crosshairs yet again when Tony Hinchcliffe was handling MC duties -- going down the line and roasting everyone.

Right after shouting Will Ferrell's cameo as Ron Burgundy -- he mentioned the classic 'Anchorman' line, "A whale's vagina' ... and then immediately said, "Which reminds me, Kim Kardashian's here." He followed up by saying a lot of Black men "celebrate in her end zone."

That wasn't even the end of it ... Tom himself eventually got a chance to take some shots at KK -- and he didn't hold back, joking she was nervous about being there ... all because it meant her kids would have to be alone with their dad.

Kim was a good sport about it all -- and her time onstage ultimately ended in applause ... but yeah, it was a tough crowd and kinda-mean scene.

No harm, no foul ... like we said, she rolled with the punches well enough -- and even dished some digs of her own at TB12 ... including some cracks about O.J. and Caitlyn Jenner.

All's fair in love and roasts.