I used to think the way I masturbated was strange, but now I'm not so sure.
I discovered masturbation very early, and first discovered orgasm by thrusting against my mattress. By the time I was about 10, I was beginning to leave a little wet spot of clear fluid in the sheets after my orgasm. When I was just a few months away from my 12th birthday, I had my first real ejaculation of thick, white semen and started having to wipe up my sheets after each session. I was fascinated by my new ability to ejaculate, and would often smell and taste my semen, or rub it on my body. For some reason, I had never masturbated to orgasm in any other way up to this time and 'humping the bed' is still my favorite method.
Anyway, soon after my first ejaculation, I began looking for a way to masturbate away from home and my mattress. I started thinking about the physical aspect of what I was doing and decided that if I took my open hand and rubbed my penis back and forth on my abdomen (like a windshield wiper), I could produce the same effect (since in bed I would move from side to side rather than up and down). With a little experimentation and the addition of a generous amount of spit, I was able to have an orgasm anywhere by rubbing my penis against my body! The common 'fist method' didn't occur to me until much, much later.
So, right into High School I would hump my bed first thing after school and before sleep at night (it got to the point where I would just fall asleep in my 'wet spot' without bothering to clean up) and use my 'windshield wiper' method every morning in the shower or on the toilet, or if I had to have a wank in the boy's room at school.
It wasn't until my Sophomore year, when I had a real sexual experience with another guy, that I even knew about the fist method. When my friend showed it to me, two things happened: I liked the fist method, but it still wasn't as good as my old way--and, I became very embarrassed about the way I masturbated because I began to think it was somewhat unusual. While adding the 'fist' method to my repertoire, I used my old ways more often than not and only in private--when fooling around with my friend, I used the 'fist' so as not to get found out as a 'freak'.
It wasn't until I got to college that I discovered that I was not the only guy who humped his bed or used the 'windshield wiper' method--one of my roommates admitted that was how he masturbated, and we did it together. Even so, it was many years before I felt comfortable discussing or demonstrating my methods to a partner.
It would be interesting to hear from other guys who have used these methods almost exclusively and whether or not it made you feel weird when you learned most others did it differently, and whether you still use it today. My old roommate and I can't be the only ones!