"Party like a Fireman" is a quote from "The Wrestler" a movie made in 2008 starring Mickey Rourke. Here is what is happening: There is a famous wrestler. After 10 years, he's (kind of) retired. A (fan)girl of his asks if he wants to party. He asks "How do you want to party?" She says "Let's party like a fireman!" Then, you see him and her, in the bathroom, humping fast, standing up.
Let's Party like a Fireman!