The comedian kinda came out with kid gloves at first during Sunday's broadcast, praising everyone and talking about how big of a moment it was for all the nominees ... and for himself. Eventually, he launched into some attempted ribbing at some of the movies.

For starters, his jokes about 'Barbie' didn't land with the audience all that well -- probably because he was a little crude in characterizing what it was about ... a doll with "big boobs."

There were some groans in the crowd ... and Jo noted he only had about a week and a half or so prepare this monologue -- acknowledging not everything he wrote (or had written for him) was going to kill. And yet, he continued on with some other zingers that fizzled out.

JK made light of Barry Keoghan's penis in 'Saltburn' ... suggesting it had made its way to Bradley Cooper's face in 'Maestro' -- obviously referring to prosthetic nose he rocked.

There was a lot more -- and it was vey uneven ... lasting about 10 minutes. While he was able to get through it in the end, Twitter/X was letting Jo have it online ... with bad reviews.