A 20 year old man came to casualty with a stony mass in his rectum. 
He said that he and his boyfriend were fooling around with concrete 
mix, when his boyfriend had the idea of pouring the mix into his 
anus using a funnel. The concrete then hardened, causing constipation and 
pain. Under general anaesthesia, a perfect concrete cast of the man's 
rectum was removed, along with a stray ping-pong ball!