Step 1. Put hand warmers into a cup made of felt and thread.
Step 2. Jizz into cup, and wait for it to boil (or get really hot)
Step 3. Stick testicles into cup.
Very handy for the instance where your testicles are so cold, they retract through your ass.
After Vrushabh Doshi's Cleveland Steamer outside, he was in need of a thread cup to heat up his balls.