One of my favourite ways to masturbate is in my shorts. When I was about 15 I was playing with myself as I lay on my bed in just my shorts and before I could stop myself I shot my load and soaked my shorts. It was an amazing orgasm and I loved the feel of the thin material clinging to my hard cock and the sensation of squeezing my cock through the soiled material. I got an instant second hard on and couldn't resist rubbing myself off again through the wet sticky cotton until I had another great orgasm.
Since then I've done this many times and rubbing my erection through the material always heightens my pleasure. Even as I type this my shorts are tenting and I keep playing with myself. It feels so good. Sometimes I go out in a pair of shorts with no underpants on and love the feel of my cock rubbing against the material. I enjoy the anticipation of knowing that when I get home I'll be able to get my hand round my cock till I shoot my load.
I like to rub myself through the material playing with the stain that my pre-cum makes at the tip of my dick, looking at the bulging shorts in the full length mirror and walking about with that bulging hard on as I get more and more excited. Then I'll rub myself slowly (my preferred method) until all my cream bursts out and soaks into my shorts. Its heaven when that moment comes.