Moldy foreskin

Its exactly what it means. But the moldy part is just old cum, anal juice, or pussy juice. Sometimes it may be infected from the nasty stuff under the foreskin.

Wife: You dtf right now

Husband: No sorry, I have "Moldy foreskin"

Wife: What I told you to wash your foreskin. I can take it of with a simple 3000 gaw gaw double handed twist.