This happened early last year at a local gym I belong to. Having finished a late swim I entered the mens changing room and headed off for a shower. Although it was a large gym the place was remarkably empty so I removed my trunks and stepped into a shower.
About three minutes into the wash I looked up to see a girl of about my age standing in the doorway, dressed in standard gym kit. She had a tight fitting top, with a sports bra underneath. Before I could see more of her, she interrupted my thoughts.
'I'm sorry, the women's showers are out. Didn't you see the sign?' I quickly apologised, saying I didn't realise.
'Do you mind if I join you?' I didn't know what to say at this point, so she seemed to take my silence as an invitation, sliding off her top and shorts and standing opposite of me, acting as if it was completely natural.
'I'm Amber, I'm sorry I joined you' I must admit it wasn't a problem to me. She had almost perfect breasts, somwewhere between a B and a C cup, and were pointed in the shower. Unfortunately she saw my eyes straying downwards, and my penis rising upwards.
She didn't mention it, and I noticed her lathering downwards towards her vagina. I saw her look up at me and smile. She leant her back against the wall, pointing her shaved hips towards me. Amber rolled her hand round her stomach and into the top of the vagina.
At this point I felt a twinge in my own crotch. I lathered up my hand and started rubbing up on my own shaft. I leant back against my own wall, and looked across at Amber. She had slid down the wall and was now staring up at me.
As she started to moan I felt my cum rising. It shot out and onto the floor and I dropped to the floor exhausted. Amber started to spasm, let out a short moan and then fell silent. She stood up, a little shakily and walked out, grabbing her towel and leaving quickly.
I have seen her at the gym since then, never in the same way, but I always think of her in the showers, with a very lucky coincidence.