There’s an art to giving the gag gift, so necessary at those over-the-hill-themed birthday parties. Aside from eliciting at least a chuckle, the item must be impractical, not offend, fit that particular person and show how much you really care. For the boy who never grew up — and that may include a few people you know — anything that shoots will do. No one will get hurt with the Marshmallow Blaster ($25). For the man who’s watched too many episodes of The X-Files or UFO Hunters, the mini remote-controlled UFO flying saucer can glide and hover and even light up (on sale for $25). For the book lover, this set of temporary tattoos ($8) proclaim, “Read or Die,” “I [heart] Dewey Decimal System” and “Book Lust.” The Homer Simpson Chia Pet is a hoot, even without donuts ($20; pictured). The Elvis Pez Dispenser set comes with a gold Elvis record — er, CD ($20). For the Star Wars geek, there’s the Storm Trooper bobblehead ($13). Inspire a little therapeutic fun with the Freudian Slip Post-it Notes ($6.50) or the Freud and Couch finger puppets, which handily double as refrigerator magnets ($13). Or for the Type A person, Despair’s line of Demotivator merchandise might make the perfect, well, demotivator. Finally, you can breathe some life into that party by passing out boxes of AtoneMints for Each of Your Sins, EnlightenMints or Sin-o-Mints ($3).