When your boobs "hang". The term derives from the udders of a cow, the all popular farm animal. see Claire Smith.
"Dude check out them cow boobs!"
"...sure id milk her. Im not one to miss the opportunity of some luscious cow boobs..."
"Theyre not just boobs. Theyre cow boobs."
Noun: The sad result of wearing a sports bra, or wire-free bra under a form-fitting or light-colored shirt. This makes your boobs look frumpy and shapeless, and resembles a cow's saggy udder instead of an attractive woman's chest.
Anyone under the age of 80 shouldn't wear soft bras. Young women are too cool for cow boobs.
Lisa made the terrible mistake of wearing a sports bra under a light yellow top. She hopes no one noticed her cow boobs.