I like time converting challenges with my sub. For example, do something for X minutes and you'll get X seconds to try to cum.
@Contact1 I mostly convert hours to seconds, but #Glitter3 is probably harsher than me on this one!
@Contact1 With time you can be harsher and convert days in chastity to seconds of stroking #EmoteLaugh
@Contact2 Minutes to seconds is actually nice! #EmoteRandom
@Contact2 It's a good way for #SubName to prove he is a good submissive!
@Contact3 I prefer not challenging my slaves with such a system. They earn orgasms when I decide, and they don't know how much they have to work for it.