Kim Kardashian's backside has left many heads spinning, but it disoriented "Ridiculousness" host Rob Dyrdek to the point where he couldn't remember exactly where it is.

In a bonus scene from the most recent episode, which featured Kim's sisters Kendall and Kylie Jenner, Rob asks the girls about Kim's notorious "bosom." And though they seem to know he's got his anatomy phrases a bit mixed-up, they play along.

After Rob asks the girls if the Kardashian-Jenner clan has any nicknames for Kim's "bosom," he can only think to declare, "A great bosom is a great asset to have in life." Finally, a producer feels compelled to step in and enlighten Rob by pointing out, "You might want to say butt instead of bosom, because bosom generally refers to breasts." Mistakes happen, man.

"I didn't catch it!" Kendall says in an effort to console the increasingly embarrassed stunt man, but the damage has been done, and all Rob can do is walk off his shame in front of the giant laptop's glow. You've just gotta learn some lessons the hard way...

Check out the clip, and tune in to the next "Ridiculousness" episode Thursday night at 10/9c!