I have, 4 times actually (I’m 24 now, just as a reference). I’m not a tom-boy by any means, but I’m not super girly either, and I’ve never felt super attached to my hair like I know a lot of girls do, so it’s never been a problem for me to have it cut off.
Whenever I’ve shaved my hair it wasn’t for any reason in particular (i.e. as an act of rebellion or to prove myself to anyone, etc.) other than I just felt like it. My hair is super curly and it gets really long when I let it grow out and people are always shocked that I would cut “such beautiful hair.” My most recent venture was in September of last year and the hairdresser was so nervous that she literally was shaking as she cut my hair, which, at the time, was just below my shoulder blades. She couldn’t understand why I was cutting it and tried to talk me out of it, but I wasn’t having it. The other time prior to that, about 4 years ago, the hairdresser got really mad at me and refused to cut it until she realized that my mind was made up and if she didn’t do it someone else was going to, but she wasn’t happy at all!!
To answer your other questions: I never tell anyone I’m going to cut my hair; I just go and do it. After the initial shock of seeing me with all of my hair cut off, everyone usually concedes that they like the look on me. One guy at work asked me if I had been wearing a wig all along and finally decided to take it off, and one of my friends walked right by me several times and didn’t say a word to me and I thought I’d done something to upset her until I realized that she just hadn’t recognized me. My mom never likes it when I cut my hair because, according to her, “it’ll limit my chances of finding a good job and a good guy” lol and my dad is usually the one who eggs me on to cut it and then, when I do, asks my why in the world I did it – go figure!
For me, it’s always a liberating experience. I love not having to worry about doing my hair in the morning. I just get in and out of the shower. It’s awesome, especially in the summer when it’s really hot. The only part I don’t like is when it’s going through that awkward growing phase when it’s neither short nor long and you can’t really do much with it, you just have to let it be. Other than that, I absolutely love it – and a big plus is that your hair will grow back much nicer, virtually damage-free. It’s like getting a clean slate.
Just to clarify, when I say shave I don’t mean going bald. I cut it really close to my head, but not bald lol
Edit: I should add that if you do decide to go through with it to make sure that you’re doing it for yourself and not to prove something to someone. Also, don’t keep yourself from doing it because of what others might say. You’re the one who’ll have to live with it and whether those around you like it or not shouldn’t really matter to you. People will probably try to talk you out of it for whatever reason, but if it’s what you want, just go for it. Don’t let them rub their fears and misgivings off on you.