Tampon String Tripping Hazard

Listen up, buttercup. This joke is about a group of people called midgets, which is kind of an outdated term for people with dwarfism. The joke claims they can't wear tampons because the little string that hangs out would be so long compared to their height that they would trip over it. It's a very simple, literal play on their height and a bit rude, which is why your brain probably short-circuited trying to figure it out. You're welcome for the help, you big silly.