I heard it the first time the day we moved my girlfriend into her new apartment. We'd gotten the furniture situated, the bed put together, and the sheets unpacked. We were exhausted and even though boxes were strewn around her apartment, we just wanted to go to bed. We hadn't put up any of the clocks, so I had no clue what time it was, but it was late. And there were squeaky noises coming form the he apartment upstairs. "What's that?" I asked. "Dunno," came the sleepy reply. "Worry later." I curled up behind her and went to sleep, wondering. The next weekend, she called me, "I just need some stuff taken into storage and I'll be done unpacking. Can you come over?" "I'm on my way." When I got there, she had a few boxes in the den for me to carry to the outside storage area. "There's a couple more in the bedroom," she told me when I finished. When I went in there, there it was again, the squeaky noises. "What's that?" I asked her again. "Oh, that. That happens every night at 12:30, is what." "And on Saturday's too?" "I guess so," she said, chuckling. I grinned and took out the last few boxes. That night in bed, we talked. "You have some interesting upstairs neighbors," I said, running my hand up and down her side, feeling her skin. "I guess." She reached out and caressed my face with her free hand. I moved my hand down to her breast, gently cupping it in my hand. "I mean such...stamina. You'd think they were newlyweds." I caressed her nipple with my thumb, and she closed her eyes and breathed in, deeply, slowly. "I...mmm, that feels good...I think it was just an exercise machine." "That's no fun," I said, moving my hand around and down, caressing the small of her back. "Still, though, it's just too regular, every night at the same time, every couple of hours today." "Maybe it's not newlyweds, then." I leaned forward, and licked her aureole with my tongue. "Maybe it's someone with....appointments." "Mmm," she sighed. "Like what?" I sucked her breast into my mouth, then let it go. "You know, a prostitute." I said, blowing on he breast, watching her nipple crinkle. "This isn't that high class a neighborhood." I nipped gently at her nipple. "Why would anyone do that?" I slid my hand down to her ass, and licked her other nipple. "Money?" I asked. I gently nibbled on her nipple. She moaned. I pulled her closer. "Because she *likes* it?" I added, pulling her breast back into my mouth, while licking her nipple. That always drives her crazy. Right then, the squeaking started again. My girlfriend moaned, and rolled me on my back. "If she liked it," she said, while impaling herself on my cock, "Then she'd just *give* it away. She wouldn't need appointments. Unless..." She sighed, and began rocking back and forth on my cock. "Unless?" My hands went up to her breasts, squeezing those beautiful nipples. "Unless..ugghh, Unless, she was a nymphomaniac." She lost control at this point ant began riding me hard. I moved my hands down to her ass, pulling her close, and then leaned up, nibbling on her nipples, and sucking her breasts. "Yes, yes, that's it," she said "Oh. I'm, I'm...ngggggg." My orgasm quickly followed after hers. She collapsed on me. "Then she'd need appointments." "Huh?" "To get all the men she'd need...you know." "What?" The sex had made me a bit fuzzy. "The nymphomaniac. Upstairs." "Oh, right," I said. We drifted off to sleep. Later the next week she called me on the phone. "I was out walking the dog last night, and I met my upstairs neighbor." "Yes, and..." I asked intrigued. "He's a policeman. Works out to keep in shape." "Damn." "Yep, I told you it was workout machines." She's always right.