Haha! I've done the very last one a couple of times. And I love the Welsh one, since I am a quarter Welsh and have can put on a pretty convincing Welsh accent. Here's something else you can do with very little:

Make people yawn
When using public transport, or are at school or work, yawn every now and again. Make sure it's a big, wide yawn, accompanied with sound. Yawning is contagious! Count how many people you can give the yawn to. Can also be made into a competition.