It only works because we still amuse each other. After we have been working with other people, it is so refreshing to laugh unreservedly when we are back together again.

I remember once having to stop performing when I thought an elderly man a few rows back from the front was actually going to die because he was laughing so hard.

People expect us to be different, but we're not. We're very similar people, and it's because we're so similar and close to each other that we make each other laugh - in fact we make each other laugh more than we make anyone else laugh.

There is a lot of rubbish written about toilet humour - people saying it is childish and pretending it is beneath them - but there is no doubting the effectiveness of a really good willy gag.