According to Urban Dictionary, "gagged" means "to be amazed or stunned by someone or a situation of some kind." The site says ...

“Shipping” tends to involve fans imagining beyond the actual events of a television series or movie. The term is closely associated with fan fiction culture, or originalstories created by fans based ...

The term “slay”, refers to someone who is stylish or successful. It can also mean to impress someone very much or to be very good. It was voted children’s most preferred slang term.