It is rude to pretend to hit someone.
Kell and Neon are talking with some girls during lunch at High school and Neon makes a corny joke.
Kell wants to respond to the corny joke.
Kell follows up with another corny joke.
Kell raises is hand up in a faux slap position to indicate silliness.
Kell feels good about being a gentlemen.
The girls take it as machismo and Kell loses his friendship with them.