These are the 10 worst reasons that I've actually* heard (possibly said, don't judge me) for turning down sex. And if you want to be especially off-put, imagine a guy saying this about receiving oral.
10) "I just got a haircut." Maybe his coiffure is elaborate and prone to mussing. Maybe he doesn't want to get itchy clippings in the bed.
9) "The Sox just won the series, baby, let's celebrate with the boys at Sully's." The '[insert team name] just [won/lost] the [insert big game], I want to [hang out with/call] my [friends/dad]' plan is respectable. Too bad that the guys that won the game are probably having sex just soon as they get out of those uniforms, if not before.
8) "I was planning to watch Beaches tonight, it's due back tomorrow." While I've never heard the Beaches part, if you're watching a movie rather than enjoying carnal whathaveyous, you might as well be watching Beaches. Like if you're white, you're Ben Affleck.
7) "I feel kinda gross, right now." Hey precious, we all have to deal with winter weight. You can keep your shirt on or turn the lights off if you have to.
6) "I'm starting to get a cold." There are certain drips that makes turning down sex chivalrous, your nose isn't one of them.
5) "I've got a basketball game in the morning." Yo, Raging Bull, Delilah over there isn't going to rob you of your strength.
4) "My horoscope advised me to not doing anything rash today." Knucklebones, tealeaves, crystal balls, Tarot cards, chicken blood and magic 8-balls aren't the most effective tools for decision-making. Try a pros and cons list, son.
3) "I would, but you'll never be able to enjoy sex with another guy again." Sweet line, Mystery, she'll be banging down your door faster than a hummingbird toots.
2) "I'm feeling a little exposed. Could we just sleep next to each other?" The cuddle monster is back and he's manstruating.
1) "Yeah, I kind of have a thing for someone." And "I have a copy of the swimsuit edition sitting on the tank of my toilet."
Some of these stupid things he may be honest mean and some of these things he thinks will make you want him more but there's just as good a chance that he just ain't into you. Or he has diarrhea.
*Note: There may be some embellishment, what do they say about the truth getting in the way of a good story?