This happened several years ago when I used to live in a condominium complex.
The nice thing about living in the condo's was that it was mostly younger couples or singles in their twenties and thirties who lived there. I would see many attractive young women around the complex checking their mail or on their way to their car.
I would look forward to spring and summer when the weather was warmer and people would leave their windows open. On several occasions I would hear the distinctive and unmistakable sound of a woman experiencing sexual pleasure: short gasps or moans, sometimes even followed by hot words of lust!
One time I was lying in bed, trying to go to sleep and I heard one of my female neighbors having sex. I heard quick short gasps, 'oh, oh, oh,' then quite plainly 'mmmmm, yes!' I got instantly hard and my heart started hammering so hard with excitement I thought it would pound right through my chest.
I stripped off my underwear and lay naked on top of my sheets, stroking my rock hard cock as I listened to my neighbor as she made those erotic hot sounds of sex. Her moans and gasps were getting faster and more urgent, it sure sounded like she was getting fucked good and hard and about ready to cum.
I could feel myself getting close and I wanted to try and time it so that I had my orgasm as she peaked and went over the edge, too. I had one hand stroking the shaft of my cock, and the other was tugging down on my balls, making the skin on my shaft nice and tight, just the way I love it. My neighbor's sounds changed from gasps to moans which sounded like she was about ready to cum. I worked myself right up to the edge of my own orgasm, imagining my neighbor getting fucked doggy style, her breasts swaying back and forth to the rhythm of the pounding she was getting, maybe she was even reaching under herself to rub her clit or pinch her nipples.
I lost control as I heard her go into a long wail, signalling she was cumming. I felt my orgasm trigger, the cum starting to rush up the shaft of my cock. I had my balls tugged down to wonderfully constrict the rush of cum up my cock so that the pressure built up to intense pleasure. I couldn't contain it, and my cum spurted out in a long hot stream covering my stomach all the way up to my neck! The pleasure and release of hearing my neighbor having sex as I spurted was intense.
I miss living in the condo's.