Idiom Idiot

Having lunch with my genious pal Jim yesterday, and the conversation went something like this:

Jim: ...that would make me happy as a camper.
Mark: Do you mean 'that would make me a happy camper'? Or do you mean 'happy as a clam'?
Jim: No, I don't think it's either one of those... maybe it's 'happy as a pig in '... something.
Mark: Slop? Happy as a pig in slop?
Jim: No... I think 'happy as a pig in a blanket'.
Mark: Maybe you mean 'snug as a bug in a rug'.

Jim sort of looked at me as if he'd never heard that one before.