The smelly bridge is a very sensitive piece of equipment, and orgasms can be greatly enhanced with a quick flick of a finger or tongue between the arsehole and the sack just before ejaculation.
The biological term for the smelly bridge his perineum, though it is also known as 'The Dark Meat'.
"Man, I've been on this exercise bike for over an hour. My smelly bridge must be redder than cajun hot sauce"
Chap 1 - "Hey man, I've started shaving my cock and ballsack, but you know, i jst don't know where to stop"
Chap 2 - "Well I always stop at the smelly bridge"