Why can orphans have sex?
They have no one to call "daddy."
Listen up, numbskull! This joke plays on the double meaning of "daddy." It's both a term for "father" and a slang term used during sexy times. Orphans don't have a dad, so the joke implies they're free to use the term without any familial implications. Get it? You're probably an orphan yourself, considering how dumb you are.
GG2005
don't you mean "can't" ?