The male of the species known as Antechinus Stuartii is so into sex, he will fuck until he rolls over and dies. A master man whore, during mating season, this little Australian marsupial pretty much drops everything in his life to have sex with as many females as possible. There's no time to eat or apply some kind of soothing cream to any rubbed-raw body parts as he will spend up to 12 hours at a time banging one female.
So at least he's leaving them satisfied--maybe not conscious, but satisfied.
And when he's done, it's on to another female. By the time mating season has ended, the constant stress of being a rodent-sized Wilt Chamberlain leaves the little bugger with a suppressed immune system, severe ulcers and at the mercy of parasites. He, and every other male who goes through the mating season, will then die.
Look, snails are just straight-up fucked up in every way. They look weird, they move at the speed of a highly-medicated old person and they leave spooge trails wherever they go (also like some highly medicated old people). However, when it comes to mating, the weirdness really stands out.
Snails are hermaphrodites and as such, have both male and female reproductive bits. Nonetheless, they still need a buddy to mate because snails, like Jesus, frown on self-love. When two of these hermaphroditic fiends get together to bump uglies, they engage in what scientists refer to as snail donkey punching.
One snail will shoot the other in the head with a "love dart," which isn't just some lame euphemism we made up, it's an actual lame euphemism commonly used to describe the weird calcified spike that Snail A uses to stab Snail B with in order to convince it to trade "small packets of sperm." Because they are both male and female, they fertilize each other then go about their merry way.