Here's one we guarantee you haven't heard before. A concerned citizen makes an emergency call to police in Berlin ... because foxes are having 'abnormally long' sex in his garden. 

Not surprisingly, Berlin police showed little interest in the randy foxes (and had some choice words for the caller for wasting police time). But it seems the concerned citizen was simply worried about the animals' welfare, fearing the pair had become stuck and might injure themselves permanently.

It might sound like a sexual escapade gone wrong (and the man was right, the foxes were stuck), the mating pair was actually stuck on purpose! Like their wolf cousins (family Canidae), foxes take 'two become one' a little more literally than most animals by actually interlocking until the deed is done – a strategy known as 'copulatory tying'.

This long-time lovin' can last over an hour in foxes, and that comes down to one thing: slow swimmers. Fox semen is slow-moving, so the male penis expands to stop the pair from separating before ejaculation. This up-size strategy also stops the female fox from moving on to bigger and better, hence eliminating some competition from rival males. So fear not citizens of Germany, there's nothing to see here ... just a bit of evolutionary genius!

Want to know more? It's all explained in our episode of "Wild Sex: When Sex Gets Stuck!"

Top header image: Doug Brown/Flickr