A guy needing to be locked in chastity.

Really, me? Well I'm flattered bestie, it takes a truly special boy to be able to admit you can't be trusted with control of your orgasms, of course I'll be your keyholder! Are you wearing it right now? Then quick, give me the keys before you change your mind and we can get started.

Now that I own your cock I suppose there's no use in bearing around the bush, what's the longest you've ever gone without cumming? A month? Not bad I suppose, given how long you've been playing around with this I was hoping you'd be used to longer- though I suppose if you had any willpower you wouldn't need me would you.

I'm thinking a year to start off, just to establish a baseline of sorts, and with regular edges starting after the first six months. Some of your sentences after that may be shorter, some may be far longer, the point is to build your chastity stamina and teach your body and brain that it has absolutely no say in when you get pleasure.