Warning: This video contains some adult language.

Zach Galifianakis
finally did something we’ve all been wanting to do lately: Smack Justin Bieber for all the dumb stuff he’s been up to.

The singer was the latest guest on the "Hangover" star's hilarious web show, "Between Two Ferns" -- where Zach ripped on him for smoking, speeding, peeing in buckets and his controversial comments about Anne Frank.

"It's really exciting to talk to you, especially right in the middle of your public meltdown," Galifiankis tells a straight-faced Bieber.

While the interview starts out innocently enough, tensions escalate -- and soon enough Zach whips Justin with his belt.

Sure, Justin's in on the joke, but it's still worth a watch.