A wheelchair user hurtles down a slope towards the waiting jaws of a crocodile. Someone was having a chuckle when they came up with that one, more at runaway political correctness than disabled people we hope. There are some seriously bizarre and funny signs tucked away in the zoos and wildlife parks of the world. Some are dumb, some are witty, some are cruel and some are silly. Some are graphically just plain weird, while others may as well have been written by the animals – who still find a way to have their say. Here's our compilation of 20 of the best.