1. The "I was going to masturbate, and then you popped up on my Newsfeed" booty call. You broke up on good terms and sometimes you call each other up to hang out, but you still can't figure out what the rules are now. Sometimes your ex is totally down to swing by at 3 a.m., and sometimes they act offended. Other than the occasional cold shoulder via text, it's a pretty alright setup.
2. The "we ran into each other in a bar and we always had good chemistry. "This is effectively the booty call but it isn't prearranged. You just see each other out, and you're like, "Sure, why not?" Better than going home with someone you don't know.
3. The hate-fuck. This one is inexplicable. You hate your ex. Your ex hates you. You meet in a parking lot for 30 seconds so you can get back your hoodie. You have the best sex of your life in the back of one of the cars. For some reason, the revulsion makes things hotter. Science has yet to figure out why.
4. The "we broke up but can't let go" torrid affair. It's like your post-breakup sex, but you're stretching it out over months. You don't want to be together anymore, but you also can't stand the thought of being alone. Although you're still having sex on the regular, you're also postponing the inevitable pain of the actual breakup. Bonus points though, since the whole sneaking around since you're not a couple anymore makes things kinda hot.
5. The "we're at a wedding and emotionally vulnerable" late-night hotel sex. You're watching the bride and groom, and thinking about how you're emotionally unfulfilled and you'll probably end up alone. Then you spot your ex and can't think of a reason you shouldn't give it another shot. The next day you both sober up and never speak of it again.
6. The "I haven't seen you in 10 years and didn't remember that you're kinda shitty" sex. You meet back up and some of that old spark is still there. You end up hooking up and the sex is terrible. Then you remember they are terrible. You sneak out and swear to never do this again.
7. The "are we getting back together though?" You meet up to have a "talk" or so one of you can pick up some of your stuff, and wind up having sex. The whole time you're thinking, Are we getting back together? It's not bad sex, but the whole thing is very distracting.
8. The overly emotional, post-breakup sex. This one is, admittedly, a bit of a cheat, since you just broke up, but sometimes the best way to say good-bye is to quietly bang in each others' arms. It's still really, really sad sex, so this one isn't so great.
9. The "I kind of want to have sex but I can't figure out your intentions" sex. This one is hands down the most awkward. You're totally down to fool around with your ex a bit, but you can't really figure out what their deal is. Do they think you're rekindling the romance? Do they just want the same thing as you? Do they think this is a hate-fuck but you don't? You definitely can't stop the action to ask; that's a real boner-killer.
10. The "open the floodgates" hookup. You figure you're just backsliding casually for one night, and then your ex starts texting you constantly and acting as if you're back together. You have to break up with them ... again.