[RiskyFlame]

Tie your balls together in a way that balls sack alone can drag something heavy over the floor. Run a rope/chain from your sack to something heavy *. The rope/chain has to be long enough so the weight will be dragged over the ground behind you (e.g. 2 metres long). You will create yourself a route/parkour to drag the weight with your balls sack all the way to the finish. To force yourself to finish the parkour, place the key to your handcuffs (and optionally your ankle cuffs) at the end of the parkour.

After preparing the parkour and placing the keys at the finish, duct tape both your hands the best you can so you won't be able to use your fingers. Put several socks over your hands and cuff them in front of you. Start the parkour and at the end, use the keys (with your mouth) to unlock yourself. Optionally, put the keys in something messy or filthy like a bowl of urine, faeces, messy food, etc.

* If the parkour involves lifting the weight from the ground (stairs), opt for something you can actually lift from the ground. Otherwise, choose a heavy weight that you can barely drag over the ground.

Edit: if possible, wear a collar so you're able to put the handcuff's chain through the collar so you won't be able to use your (almost rendered useless) hands to lift the weight.