This jack off technique is called Plasticine Pleasure cos it’s a bit like the fun you had rolling lumps of plasticine when you were a kid.
All you do is place your cock between both hands and rub back and forth as if you were rolling a nice fat slab of plasticine into a meaty sausage shape. You can start jacking off to this one before your cock is fully erect, and because quite a lot of rubbing is involved to get the level of friction going, lube is strongly recommended.
Note: Never ever let the kids play with this particular lump of plasticine because you will have to sign the sex offenders register.