Frozen
Or perhaps you prefer my tits. I hope your not stroking yourself it will only make your stay in chastity all the more difficult and harder to squeeze into your cock prison. Anyway the rules.
You are to lock your cock in your chastity cage and then place the key in one of the empty ice cube holes. You will then pour water into all the slots, place them in the freezer which means you should have 32 ice cubes and only one will release you from your chastity prison.
Don't do it yet, you haven't heard how you will be winning that key.
Each day you will be given the chance to win an ice cube by completing a task. Every ice cube you win increases the chances of you unlocking your cock prison. Everyday at a time you have decided you will get a bowl on the floor, blindfold yourself, randomly shuffle the two trays of ice cubes so you don't know which your key is is in and then empty one of trays into the bowl. Then you will take an ice cube and suck it until it has melted, if it has a key in it then great unlock yourself, if not pick another cube out still blindfolded until you have used up your allowance of ice cubes. You will then put the un-sucked cubes back in the ice tray, fill up your empty spaces and ensure the ones that have been in the bowl are topped up.
As you can tell if you complete every task the very maximum you can spend locked up is 32 days and the odds of it being that long are very slim. But if you refuse tasks, who knows how long you'll be caged for.