Back Sac

The practice of pulling your testicles between your legs until they become rested on or near the anus. Performed by guys with the name of Chadd.

If you don't quit back sacking, your testicles will become streched out. \

Don't back sac me bro!

Sack to Back or Sac to Back

Sack to back is the term used when two males ride a motorcycle or scooter together.
Also referred to as "Butts to Nuts"

Those guys are riding "Sack to Back or Sac to Back"