Which doesn't belong and why?

A crowded field....someone has to go
Don Imus's sidekick Bernard McGuirk used to impersonate the local Cardinal from New York and at the end of his gag was a "contest" where upon he would list 3 improbable things and as which one "didn't belong and why".

It was funny, obscene, and and improbable. 

So what is your pick? Not of the folks above, but between funny, obscene or ........?