The former "SNL" star says one particular musical guest ditched the dress rehearsal and sent their choreographer in their place -- which Rihanna did in 2012.
But we have our suspicions.
The comedian and former "SNL" star stopped by Busy Philipps' new late-night talk show, "Busy Tonight," where she pressed him to reveal some BTS drama.
"What was the worst behavior you saw from a guest or a musical guest or a cast member who was more famous than you?" she asked, adding that he didn't have to "name names." (Why'd you have to go and do that, Busy?!)
"There was a musical guest who didn't perform the dress rehearsal," Killam explained. "We do a dress rehearsal show, like a full show, at 8 p.m. And their choreographer was performing for them!"
"They just kind of mouthed it and went through the motions," he continued. "It was the oddest musical experience because it was like we were all at a friend's birthday party who wanted us to treat her like a pop star or something. And we were all kind of like, 'Alright, yeah, that sounds just the same. We're not at all disappointed in this. Cool, cool.'"
Philipps laughed and moved on to the next topic, but we didn't. We did some digging.
Turns out, Rihanna caused a stir back in 2012 when she skipped out on an "SNL" dress rehearsal. At the time, her reps said she was "sick and needed to save her voice for the live show," though TMZ reported that her absence "did not sit well with the show's producers, including head man Lorne Michaels."
At the time, the publication also reported that Rihanna's choreographer stepped in to take her place during the rehearsal, which lines up perfectly with Killam's story.
TooFab has reached out to reps for Rihanna for comment.
"Busy Tonight" airs Sunday through Wednesday at 10 p.m. ET on E!