6 less than pleasant mating rituals of the animal kingdom
Some people may consider human mating rituals to be pretty unpleasant. I’m not talking about girls lying or guys cheating. There are plenty of relationships that have unpleasant aspects but this title is a little facetious in that these instances are not just ‘less than pleasant’. These rituals are painful and horrifying and if any human attempted them they would earn a special place in Hell which is probably within eye sight of wherever Hitler is.
Praying Mantis:
Most people have heard about this one. After mating the female will often eat the male. It’s interesting that this happens almost all the time in a lab and much less frequently in the wild. The Praying Mantis is a very observant insect and they it may only happen when it know it’s being matched. Possibly to erase all evidence that she just hooked up with a really ugly mate. Males will also wait to dismount the female until the most opportune time to escape.

I'm not getting off until she falls asleep
The female will usually start with the males head and sometimes the male will continue mating without his head. This makes them similar to humans in that they only have enough blood to control one head at a time. Clearly they’ve been doing something right because in cold climates most Mantii die during the winter. That’s a lot of pressure every year because if you mess up you’re extinct. - Source
Redback Spiders:
This is another insect where the female will take the house, the kids, and its mate’s life. For some reason the males are the ones who still need to initiate the courting ritual. Presumably because Vince Vaughn isn’t around to tell them it’s the biggest mistake of their life.

Congratulations, you got one vagina for the rest of your life
They pluck a fiber of a web and if the female is in the mood… or just hungry she’ll give him the go ahead signal. The male doesn’t even put up a fight. He basically assumes the position. This position entails him curling into a ball and rolling right into the females open mouth and fangs. She will suck some juices out of him for a while as they go at it then he will pull away. Most would assume he would take his change at freedom and go, especially since he’s already planted his seed. You would be wrong. He goes in for second… givings? at least twice more before she finishes him off.

This may or may not be two Redback Spiders
Male Redback spiders either have an incredible sense of duty or are some of the dumbest things on the planet. - Source
Bedbugs:
Alright here is one where the male makes off a little better than our last two mama’s boys. This guy is not about to be told what to do and in no way will he endanger himself. We aren’t sure if he has a system to pick a mate or if he just goes with whoever is closest. There isn’t much evidence of the female doing any sort of enticing either. Probably because she knows what’s coming. What pray tell is that? Traumatic insemination. It actually sounds better than what really happens. It sounds like they force themselves onto the female and do whatever they want. Instead they completely ignore the female sex organs and impales the female’s body cavity with their medieval lance-like dick.

Don't let the bedbugs bite, or stab you with their dick
They don’t talk much about what happens afterwards. I assume the female limps around long enough to have the babies then dies and the male just looks for someone else to stab. - Source
Fire ants:
Ants have a very interesting and complex living structure. It’s broken down between the queen, female workers and male drones. The workers have no need for the males and so in an effort to keep things as neat and tidy as possible they kill them any chance they get. Now the drones aren’t big fans of this but they can’t do much about it and no one seems to care. The queen does occasionally need drones to mate with though and the colony won’t last long if the stupid short sighted females kill all the males.

This was the second link that came up when I google "queen ant" so I assume it's accurate
So the queen calls the females out on their killing ability and lays as many male eggs as possible. The females drop everything they are doing and go into killing overdrive. The plan is that at least one male will be competent enough to survive and mate with the queen so she can once again be able to regulate the sex ratio in the colony. Also the males die after mating so it’s kind of a lose lose for them. It’s got to be pretty rough for the male drones when the queen isn’t looking for a hubby. - Source
Banana slug:
These guys are hermaphroditic which means they have both male and female reproductive organs. They are also capable of self fertilization. The fact that they are on this list tells you that they opt for a much worse method instead. First off they release a slime to attract a mate. Each slug will eat the others slime to determine if it’s worth mating. Trust me this is a big decision. At this point I want to point out that most Banana Slugs are roughly six to eight inches in length and sport a dick that is also roughly(no kidding) six to eight inches in length.(it’s latin name is dolichyphallus aka giant penis)

It's body is hidden behind his dick
What happens after fertilization scientists call apophallation. The dick gets stuck inside its mate. I hate it when that happens. Apparently the only way to remedy the situation is for one of them to bite off the penis. Afterwards I suppose they just go their separate ways and never talk about it again. - Source
Bees:
There are a few bees that use this method of procreation. Once a queen bee has become sexually mature and killed off her rivals she goes on a little joy flight with the cream of the crop of the male drone population.(about a dozen out of tens of thousands) They vie to be the one who’s genes get to create the next generation.
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Bumble Bee always wins
For the winner it is a bitter sweet victory. They do get a few minutes of bliss but this is followed by… you guessed it…. Their balls exploding off their body and plugging a hole in the queens baby canal. This evolutionary act makes sure that only one drone gets to fertilize the queen and maintain a healthy generation. This is probably not much of a condolence for the dead bee with the exploded genitals. This sheds a whole new light on that Bee Movie with Jerry Seinfeld. - Source

...and what is the deal with exploding genitals?
Anyone who felt humans had the most disturbing sexual behavior have hopefully changed their mind. Demented and insane people aside, no person would do the types of things that have been mentioned above. So if you see any of these animals you might be doing them a favor when you crush them under your shoe. It’s a much more merciful death than what some of their friends may experience.