knuckle dripper
A knuckle dripper is when, after a long, hard day of beating your meat, your volcano tries to erupt at the end of the day, and it ends up rolling down your knuckles like a tear running down your cheek.
Wife: "Honey, I thought you were gonna, like, give me a facial. Not some knuckle dripper.
Husband: "Sorry, honey, you were at work all day."
Husband: "Sorry, honey, you were at work all day."