Stop Squirt September, or for short - SSS.
Similar to nnn, it revolves around women and it occurs in September, when girls must not ejaculate for the entire month. Might seem easy at first, but is very challenging for those, who aren't new to the whole masturbating thing, which requires a great amount of willpower.
Of course, for those who don't masturbate at all or started very recently, such challenges are easy to do, but not for veterans.
-"Is Anna still doing that Stop Squirt September challenge?"
-"No, she failed it"
-"Damn. She couldn't hold any longer"