Noun: a build up of rosin, dead skin, and sweat on an instrument's bow, often located along the lengththe stick, on the frog at the ferrule and where the frog and stick meet. This can vary in color from light yellow, green, dark brown, or even black.
"EWWW! There's so much hand cheese on this bow it's still sticky!"
"It took me an hour an a half to get all that hand cheese off that bass bow. The owner didn't even recognize it when he picked it up. He was so happy he even gave me a tip!"