One I hear on occasions and just pretend i've never heard it before and laugh is:

"One of my friend's grandmas had a cat that died recently. She phoned up the vet who said to bring the cat into the surgery for it to be disposed of correctly. The problem was that the grandma didn't have a car so she decided to put the cat in her rucksack and take the bus to the vets. Just as she was getting on the bus with the rucksack in her hand, a young lad ran up to her, punched her in the face knocking her over and stole the rucksack. Bet the chav had a right shock when he got home thinking he'd stolen something valuable."