I guess you could call this a technique learned from necessity. When I was fourteen and just getting into masturbating a lot, I spent the summer with my dad in his studio apartment. Although I'd usually jerk off a few times during the day if I was alone, I was also more than ready when I slipped between sheets in the warm dark of the night. But I couldn't possibly let my dad find out what I was doing! Before going to bed, I'd put a couple of tissues under my pillow, to catch the cum. I folded these carefully so they would go over the tip of my penis easily when I was ready.
Most of the time when I settled into bed, I'd get a hard on. But sometimes I'd jacked-off so much during the day, my penis didn't spring to life right away. That was ok, I was patient, since it all felt good. I would lie there with just my fingers touching my penis and except for that I wouldn't move a muscle! Usually, rubbing the tip would be enough; sometimes squeezing would work. I remember that later in the summer, I discovered the pleasure of a finger around my anus, and so before going to bed I'd put some baby oil around there. One advantage of this very minimal stimulation was that I could go on for hours in a kind of drunk pleasure, approaching climax, then stopping, and beginning again.
After a long session, I would often have an enormous climax, and it took great control to keep from twitching. I found this restraint to be very thrilling. I felt like I wasn't really masturbating myself, but was tied up and passive, while I was teased and teased for a long time before orgasm finally came.
As I've grown up, and especially when traveling, this technique has proved very, very useful. If I'm especially horny, I can cum in my pants with only the slightest movement. At the supermarket I sometimes get pretty horny watching the housewives, and I've played a game: I pick a long line with a cashier that turns me on, and I might wait around until a shopper that is very sexy joins the line. Then I get in line, and gently stimulate myself until I come up to the cashier. My goal is to have an orgasm right then, at the head of the line, with the other customers and the cashier watching, but never knowing the reason for the flush in my cheeks.
Recently the bottom seams of the pockets of my favorite pair of bulky cargo pants came apart, giving me direct access through to my crotch (why didn't I think of that sooner!). This is great, but compared with what I've learned to do, it almost seems like cheating!