Rolling thumb stretch
Put your hands out in front of you, palms facing down, and let your thumbs be parallel to each other and touching one another, such that one thumb’s fingernail is facing the other thumb’s fingernail, and the knuckle of each thumb is touching the other. Now roll one thumb against the other, as if they were gears or rollers. As you do this, your hands should rotate about ninety degrees until your palms face each other, as if in prayer.
Now do it as above, but with your fingers curled (thumbs still straight), and as your hands rotate, they should end up forming a bowl, as though your were trying to contain water within your hands.
Now, as above, place your hands out and imaging you are grasping a horizontal and flexible bar, palms downward. Rolling your thumbs against each other, you can imagine the bar would be significantly stretched around your thumbs. What your thumbs are essentially doing is creating a camming action.
Grasp your flaccid dick with a grip using your right hand at the base, with your thumb on the left side. Then grasp your dick with an overhand grip with your left hand so your left hand’s thumb is also on the left side, such that both thumbs are pointing downwards, parallel to each other and fingernails and knuckles of each thumb are facing each other. Now, as described above, roll your thumbs so that your grip spreads apart. You can apply tremendous leverage this way and stretch your dick around the cylinder that is created by the pair of your thumbs.
Repeat at various points along the shaft and reverse your left hand with your right.