“I Wish I Could Do That”

In high school some of my friends and I started a band. We sucked (and I particularly sucked on bass) but it was fun, and an excuse to hang out after school.
Anyway, one day we finished practicing and went downstairs. My friend’s dog was licking his genitals (some would say he was “on vacation”). The conversation went thus:
Friend X: “Man, I wish I could do that.”
Friend Y: “I don’t know . . . that dog looks pretty mean.”

I still laugh when I think about that. Just in case you don’t get it (and it won’t be funny now if you didn’t), the implication of Y’s statement was that he understood X to desire the ability to lick the dog’s genitals.