You shouldn't mock people.
Abby said something annoying.
John wants to respond to her to show how he feels.
John takes Abby aside and tells her how what she has said is bothering him.
John looked at Abby and starting repeating what she said in a high pitched voice.
John and Abby remain friends and Abby realizes she was being annoying.
Abby and the other friends watching are annoyed with John for being rude.