Gemini is an air sign, according to The Cut, so why not go with an aviation-themed costume? If you're the crafty type, MomSpark provides directions for turning a pair of Amazon boxes into a wearable airplane. You will need some pretty large boxes for an adult-sized costume, though. If you don't want to put in quite that much work, or you'd prefer a costume that's easier to maneuver in, you could always hit up the vintage clothing stores to pull together a cute 1960s stewardess look.
Another super easy, air travel-related costume is something dreamt up by blogger Desert Chica — an air traffic controller. This costume consists of an orange safety vest (hit up your local Walmart), sunglasses, and big, clunky headphones. Desert Chica made her marshaling wands (oh, so that's what those things are called!) out of orange duct tape which was wrapped around toilet paper rolls, but an orange pool noodle would work as well.
