a rule stating that you may date/hook up with one person a year who is a 4 or lower on the attractiveness scale and noone can make fun of you to your face, if and only if you claim that person as your mulligan
repeat offenses are allowed with the same person with only slight taunting after
"Dude, you dated that girl? She looks like a pig!"
"Yea, but she's my mulligan."