Green’s Dictionary of Slang

mud-up n.

(W.I.)

1. menstruation.

[WI]Francis-Jackson Official Dancehall Dict. 34: Mud-up 1. the menstrual period.

2. of a man, his state after sexual intercourse.

[WI]Francis-Jackson Official Dancehall Dict. 34: Mud-up [...] a general reference to one’s state after intercourse.