Flying Lotus performed at this weekend’s Adult Swim Festival in downtown Los Angeles and during his set, the electronic producer brought out MF Doom to join him for a few songs. Or at least, that’s what fans thought; soon enough, the man behind the mask was revealed instead to be a Doom imposter by the name of Hannibal Buress, as Pitchfork points out.

“I know y’all know about my man MF Doom, right?” FlyLo said as the masked figure joined him onstage. After rapping along to the Madvillany track “Accordion” — which incidentally celebrated its 15th anniversary earlier this year — Flying Lotus returned to the stage to unmask the figure as Hannibal Buress. “Hannibal, what are you doing here,” he said to the crowd. “I wanted to help out,” Buress responded.

Doom, of course, has a history with Adult Swim. The Mouse And The Mask, the rapper’s collaborative album with Danger Mouse, contains beats almost entirely made up of Adult Swim samples, and Doom has released music with the network in the past. In 2017, Adult Swim was supposed to release 15 previously-unreleased Doom tracks dubbed The Missing Notebook Rhymes, but later severed ties with the rapper for undisclosed reasons.

Watch fan-shot footage of Flying Lotus’ festival stunt below.

My heart sank to my asshole @MFDOOM @flyinglotus pic.twitter.com/RP2zR1MDmO

— blue dream (@_monikush) November 16, 2019

Actually no it was fucking @hannibalburess when I tell y’all I was sick pic.twitter.com/MbTgcyD2kF

— oliver (@1lifehater) November 16, 2019

This article originally appeared on Spin.