Big scary spider bit my ass
I was on holiday in Africa feeding starving babies when I had to take a poop, I dug a hole in the ground and took a big dump but a big scary spider came and bit my ass - it hurt and I said "I say good sir, you have bitten my anus": the spider did not reply and then my ass started to swell up.
It was then I started to get scared as my ass grew bigger and bigger until eventually my ass blew up, if you are bitten by a spider in the ass you may suffer the same fate.