Your mama!

John shouted out as he made a title dance combined with a slightly humping hip movement.

"John" is not mentioned anywhere else in this chapter. This section only makes sense if Pete Gottschalk is doing the taunting and dancing. So it should be written as:

"Your mama!" Pete shouted out as he made a title dance combined with a slightly humping hip movement.

"Yo mamma!" would also be an acceptable spelling of that taunt.