Janelle Monae Blasts Nelly for Trump Performance at Grammys After-Party

Janelle Monae roasted Nelly at a Grammys after-party in L.A. Sunday night, blasting him for recently performing at President Trump's inauguration during an impromptu rap session with Anderson .Paak.

The outspoken singer/actress hopped onstage with Anderson at Andy's in West Hollywood -- which is co-owned by .Paak -- after the two had attended the Grammys at Crypto.com Arena.

We're told Anderson and Janelle began singing a medley of songs — one of which was Nelly's hit, "Hot in Herre," which totally set off Janelle.

Check out video, obtained by TMZ ... Janelle started rapping solo, changing the lyrics to "Hot in Herre" and dissing Nelly in front of a packed crowd for performing at the Trump inauguration ball.

Janelle dropped some bars, "I used to like Nelly ... but then he performed for Donald Trump. "F**k that [n word.] I don't give a f**k ... Nelly, you sold out. I used to think he was cool ... F**k you [n word.] Get a new attitude."

Pretty tough stuff ... but not unexpected from Janelle who doesn't like Trump or his policies. Nelly has also received a lot of backlash for doing the Trump gig ... but he seems okay with it all.

Last month, Nelly addressed the inauguration issue with NewsNation, saying “This is not a campaign trail. This is not anything that I feel like I’m influencing people to sway how they feel, but it’s more about the respect and the honor of being invited for what I like to call the greatest country on the planet.”