Dibs on the tailpipe

Said right dibs have been called on a girl, it's a euphemism for wanting to have a threesome where the one who calls "Dibs on the tailpipe" desires the anal position

You: "Hot chick at your ten o'clock"
Friend: "Dibs!"
You: "Dibs on the tailpipe"
Friend: "I didn't know you were into that"