BTR stands for "back to room." This term is used to explain a hook up (typically of the drunk college type) that begins in public and progresses to one of the participant's dorm/frat bedrooms. Typically, sexual acts more serious than kissing/making out occur when a couple enters a bedroom, so this term implies a more intense encounter than the simple "make out in public."

Origin: The Claremont Colleges, circa 2008. Large five college dance parties foster an atmosphere where both men and women will kiss/make out with multiple partners at a single dance party. Many of temporary couplings are not serious, but are still considered "hooking up." The term "back to room" entered conversation to describe the scenario when a couple actually left the dance party together to continue hooking up in a dorm room. Through very frequent use, it has simply become the acronym BTR.

BTR is most commonly used as a verb (see below).

Before The Revolution

Can be referred to as BTR or BTTR ( I’ve heard it both ways )

Butt thigh ratio or butt to thigh ratio.

This is used when a person feels the need to express their lack of attraction to another person because the other person has huge thighs and a flat ass. Or their butt is perfection, But that have no support so you worry about the endurance of that ass

Butt thigh ratio ( BTR) or used incorrectly BTTR butt to thigh ratio

Used to express lack of attraction to to disproportionate body parts

BTR, also known as Big Titty Raena. This midget with huge double D titties is nuts and known for her craziness by the amount of things she will do just by winning her in a game of cup pong.