I have always loved "first time" stories. Not just "the first time I masturbated," but anything you did for the first time masturbating: first time masturbating outdoors, first time masturbating with a partner, first time with a toy, etc. (I realize some "first time" stories may not be appropriate to post in a public forum. If anyone wants to PM and share stories I'd love it.)
I can start. One great memory was the first time I tried masturbating with a vibrator in my ass. This was about 10 years ago around the time Yahoo added video to their chat application. I had a phone friend that I had met in a chat room and I would sometimes play for her on camera. (Sadly she would never play for me on cam. Said she was too shy about her body... oh well.) She was into vibrators and kept encouraging me to try a vibrator on or in my ass. I finally broke down one night and went to an adult store and bought one of those "bullet vibes" on a wire with a remote control.
I met up with my friend online and told her what I had bought. We hooked up on the phone and I turned on my cam for her and she watched me while I did it. I was really afraid of getting anything stuck "up there" so I decided to put the thing in a condom and that would give me sort of a safety net should the wire break while I was pulling it out.
She was talking to me and trying to help things along but I had a really hard time getting it inside. Later on I realized if I had used lube it would have been much easier, but it being my first time I didn't think of that beforehand. And of course if I had relaxed it also would have been easier but I was pretty tense.
After some pushing and wiggling I finally got it past my sphincter and once it was past there it slid on in pretty much by itself. I was incredibly excited by this whole thing and even though I hadn't touched my cock it was rock hard. My friend told me how excited and wet she was by watching me do this.
I sat down in my chair and positioned the cam to give my friend a good view. I grabbed the remote control and turned it on low... the feeling was AMAZING. The problem was that I was SO turned on by all of this, as soon as I touched my cock I could feel it wanting to cum. I sat there not touching myself and trying to relax and get control of the situation. I finally conceded to just rubbing my thighs and around my balls and touching my cock as little as possible. My friend was enjoying the whole scene immensely with my rock hard cock sticking straight up and I was loving the feeling of the vibe in my ass, I just wish I could have played with my cock more.
Finally my friend told me she was ready to orgasm so I increased the speed on the vibe a little and wrapped my hand around my cock. She was "encouraging" my orgasm and it didn't take but a minute for me to shoot a big load on my stomach.
The final part (and the thing that worried me) was getting it out of my butt. I grabbed the cord and condom together and although it required more effort than I would have liked, it did come out successfully.
All in all it was a GREAT masturbation memory. I have used a vibe in my ass since then, but had the good sense to use plenty of lube! But I still worry about something getting stuck and an embarrassing trip to the hospital, so I save the vibe for "special occasions."