My first year at University I lived in halls of residence, an old Victorian building, in a 'I' shape, with individual rooms either side down long corridors. Next door to me was Gareth. We were both computer nerds, both with Atari STs, both on the same course. He became a life-long, dear friend.
Now, it will come as no surprise that Gareth was Welsh. So therefore it won't take a huge cognitive leap to learn that myself and a few others decided that his birthday would involve sheep. Live sheep.
On his birthday, myself and two other crazies get into a car and drive to the outskirts of Leeds where real sheep could be found. Armed with a cassette recorder and a microphone, I encouraged some of the tamer sheep to bleat into the mic and be recorded for posterity.
Once enough bleat-age had been gathered, someone produced a plastic bag and a good dollop of sheep poo was collected.
So, back home, with Gareth misdirected at the campus canteen or something, the plan was to convince him that we'd brought him a living, breathing, pooping sheep for his birthday. I made a loop of the sheep bleating tape, and after gaining access to his room I popped it into his hifi, making sure the baa-ing could be heard outside. Then all we needed to do was place the sheep poo outside his door, to complete the wooly illusion.
Gareth duly appeared, mouth agape at the (now rather stinky) pile, nervously opened his loudly bleating door, to find a tiny woollen sheep (made by myself from a ball of white wool and some googly eyes) looking back at him.
Now, to say he wasn't amused was an understatement. Even considering the lengths we'd gone through to pull off this sheepy stunt, he didn't see the funny side. He didn't talk to me for days.