Bill Hader says Justin Bieber was the worst 'SNL' guest. Here's why he's not a belieber.

Justin Bieber may have flocks of dedicated fans who deem themselves beliebers, but the comedian and actor Bill Hader is not currently one of them.

During Thursday's episode of Watch What Happens Live with Andy Cohen, both Hader and fellow Saturday Night Live alumni Jay Pharoah were prompted to dish the worst guest they encountered.

Based on their exchange, this wasn't a difficult question to answer because they both immediately brought up Bieber.

"We both know, dawg." Pharaoh joked. At which point Hader told Cohen, "Yeah, it was Justin Bieber."

Hader went on to share that most guests are super excited and well-behaved. But in Bieber's case, the young star seemed "exhausted or at the end of his rope."