The following is a true story.
I first saw another man's cock in college. I had stumbled on a black man cruising in a campus restroom. He was in a stall masturbating, waiting for guys to come in. I didn't know what cruising was at the time. I thought he was just minding his own business, stroking himself, which is exactly what I came in there to do.
So I sat down in the stall beside him and started to have my fun. He then came around the edge of my doorless stall stroking himself and showing me his big, hard black cock. I never thought about guys before but I was turned on by the sight. He started dripping cum on the floor and that sent me over the edge. I shot my load into the toilet I was sitting on.
I became very curious about guys after that. I started having cybersex and phone sex with them. I started reading gay erotic stories. I even jacked off with the black guy again the next time I stumbled on him in the restroom.
One thing I discovered was that cocks excite me. I read a story about a straight guy who is turned into a cocksucking slave by a dominate man and became fascinated with stories like that. I began to really wonder what a cock would feel like in my hand and in my mouth. I began to fantasize about being a cocksucker on my knees,having a big, hard cock dominating my mouth.
I got a girlfriend in college who was at first turned on by the idea of a three way with a guy. She wanted to see me suck a dick and get penetrated. Wasn't sure about the penetration but the sucking sounded good. But she cooled to the idea ,and never got comfortable with having three ways or group sex after that. I married her, so my bi-curiousity got put on hold.
Then I got divorced, many years later. It took me awhile to adjust and get my life back together. But eventually I decided to pursue my bi-curiousity and experiment. I went on a free gay cruising site and a guy on there sent me an instant message. I went into chat with him and was immediately amazed at the dick in his profile. It was large, white, and insanely thick. I was immediately turned on.