What's the best part of having sex with a girl with no legs She won't run away when you're done with her
Are you making a joke about people with disabilities here?
I don't see any other interpretation.
Making light of someone not having legs and not being able to get away is pretty inconsiderate. Also, saying that a girl can not run away when you are done with her comes across as pretty disrespectful, and almost seems more like rape if they are trying to get away. Just be careful with the statements you make so you do not get yourself into trouble.