A Booce is a slang word for the urethra of human genitalia of both sexes. The term has been popularized by the famous YouTube gamer, "M3rkmus1c" or "Merkmusic." It is also the surname of M3rkmus1c's faze clan character, "Faze Booce."
"Hey, would you mind taking a pretzel stick or a mini whisk to my Booce?"