Seat Jump 

When you're standing on a bus (or other public transport) as there are no seats and someone near you gets up to get off, you quickly jump into the absent seat before anyone else has chance.

*Jack & Tom are standing on a crowded bus*
*A man in a nearby seat gets up to get off*
*Jack Seat Jumps instantly into his seat*

Seat Jump by SoupOnHerHed September 15, 2011

jump seat sniffer 

1.A creepy guy who has a thing for "stews" also known as flight attendants,female variety. He is usually remarkable for his porn mustache and clothing chiefly made from petroleum-based material.
2.A loathsome creature most often found on aircraft headed for all-inclusive resorts.

Flight Attendant to colleague: "Watch out for the skeevy guy in 25C near the lav- What a jump seat sniffer!"

jump seat skeevy passenger stewardess flight attendant
repugnant porn mustache

jump seat sniffer by skyhag August 5, 2009

Jumper seat 

Take a car battery and attach it to a metal seat and make it the only place for someone to sit.

Dude my brother came over last night and we used the jumper seat on him

Jumper seat by Animal man March 23, 2013