“Drop something Romeo?” is valid. In this case, the “Did you” part of the question “Did you drop something, Romeo?” is being omitted. It’s the same as saying “Going to the store?” instead of “Are you going to the store?” Dropping the subject in sentences is rather common in casual speech in many languages, including English. I’m sure there’s probably some technical term for it, but I don’t know what it is off the top of my head.

*dropped