Consistent with a dare, like saying I dare you to do something. If a "No Balls" is refused, the refuser therefore has no balls and may be reminded of this constantly; The highest form of a dare to ever exist.
Cheyenne: "Courtney, no balls you won't chug this 12 pack in under an hour!"
Courtney: Chugs 12 pack.
Cheyenne: "Wow, Courtney has BALLS!"
61👍 15👎