a smaller version of the bra used to support a mens testicles. used mostly by old men who have saggy testicles
Man - "Dammit, i sat on my nuts again!"
Woman - "Should have been wearing your nut bra."
Man - "AHHHH!!"
Woman - "What happened this time?"
Man - "They fell in the toilet >.<!"
Woman - "You should have been wearing your nut bra."