The two main people in the show are Clive Webb (who used to be in Tiswas) and Danny Adams. According to the splendidly named its-behind-you.com, they have been appearing in pantomimes for several years, so I assumed that this would be an extended version of that. They did have a few messy bits (e.g. custard pies and water), but that was actually a fairly small part of it. It turned out to be more like a variety show, including jokes and conjuring tricks. It's tempting to list all my favouite bits, but that would spoil the surprise for anyone else who goes, so I'll try to be vague.
When I was little, I used to watch Paul Daniels perform "magic" tricks on TV, and I still have a couple of his special decks of cards. There are people like Derren Brown who do elaborate performances, but I haven't seen any of the simple stuff for a while, which is a bit of a shame. Most of the tricks they did in this show were Tommy Cooper style, by making deliberate mistakes, but there were a couple of tricks that were done properly, and this actually made them more impressive by comparison; in particular, I have no idea how they achieved one of them. There was also one trick that technically went entirely according to plan, but it was very funny because it was so basic. I may well steal that to show some of you in person.
Clowns have a bit of a bad reputation nowadays, either for being creepy or just generally unfunny. (To quote from one of Pratchett's novels: "If it was funny, clowns wouldn't be doing it.") However, that's not the case here. For one thing, their make-up is quite minimal, rather than going for the full Joker effect. They have physical comedy, and even when it's an old routine (e.g. "going downstairs behind a sofa") they did it well enough to seem fresh. There are also a lot of verbal jokes, and these aren't just the Christmas cracker type that make you groan; most of them really made me laugh. I think the main drawback to slapstick scenes in pantos is that they can suffer from a slow build-up: everyone knows where it's going, so you can think "Get on with it!" By contrast, the jokes came thick and fast, with unexpected twists and a few that were aimed at adults rather than children.
Aside from the main duo, there was also "Cousin Timoni", who did some juggling and balancing routines (almost acrobatic). I can admire the technical skill, and he got polite applause, but it wasn't really funny. In this case, the inventiveness isn't the point (since I can't copy what he did), so I'll go into a bit more detail, although I don't know the correct terminology. One of his acts involved standing on a big ball (about the size of a beach ball), then moving it along a see-saw; this meant that he had to move his feet in the opposite direction to the way he wanted to go, and when he reached the midpoint the beam tipped so the ball sped up. Another routine involved a pair of sticks with a string between them (nunchucks?), and he had an hourglass-shaped thing balanced on this string; meanwhile, there was a bow (as in archery) propped up nearby. He flipped the hourglass into the air, and it bounced off the bowstring then landed on the string of the nunchucks again.
They also had a quartet of dancers, who provided a bit of glamour. I think their main job was to keep the audience entertained for a few minutes at a time while other people changed costumes etc. backstage. Anyway, they had a few nice routines, and their music included "Smooth Criminal" (Michael Jackson) and "Hey batter batter swing" (from High School Musical 2). I really hope that the latter song isn't a cover version of something more "respectable" that I ought to recognise!
There was a bit of audience participation, e.g. getting people to wave their arms around and shout "Woo". That's all harmless enough, and being with a couple of enthusiastic people meant that I didn't feel self-conscious about joining in. Later on, they wanted people to go up on stage, and asked kids in the audience to volunteer their dads. Amy had the cunning plan of enlisting all the nearby children to point at Peter, which worked out nicely: it's not every day that you see one of your friends get flanned while dressed as a Teletubbie! (It was also fun for the kids, since they hadn't come with their dads, and this gave them a chance to get involved.)
We weren't sitting right at the front, but we were still close enough to be in the "splash zone" when they started chucking water around, so we got slightly soggy. At one point they started throwing lettuce at the audience, which seemed rather odd, but it turned out that there was a valid reason for it.
All in all, it was a lot of fun, so I'm glad I went. They're on tour around the country, so I recommend going along to see them if they appear near you.
Edit: Amy has also written a review.