Catapult
A cat belonging to a friend of mine had been indulging in a pastime many cats are fond of - bin-diving. On this particular occasion the cat had retrieved and devoured the elasticky string stuff that my friend's Sunday roast had been wrapped up with. She was a bit concerned, as this pork-flavoured, but fundamentally indigestible bit of string could have dire consequences for the cat's internal organs, but she was relieved when the cat managed to pass the string a day or two later.

However, the cat had managed to drop a fair proportion of the string, but was struggling to eject the entire thing; so after watching the poor creature strain for a while, she fetched a rubber glove, and attempted to help the cat extricate the remainder.

The cat was understandably panicked by the sensation of tension and legged it - still with half the elastic up its bum. The elastic stretched until some critical tension was achieved, then TWANG-SPLAT - friend was liberally pebbledashed.

Length etc... seven or eight feet, apparently.
(Photon, Fri 28 Mar 2008, 0:46, closed)

This Happened To Me Too
Only it was tinsel. The stupid animal had managed to eat a two foot length of tinsel.

Seeing it dragging it's sparkly arse had me in fits for days
(Legless Internet Ninja - We Own The Net, Fri 28 Mar 2008, 3:09, closed)