At the Derren Brown (not sure what to call him - magician? Hypnotist? Con artist? Antichrist?!) show, Enigma, one section involves mass hypnotism of the audience. A strange note is played, and much mysticism ensues, the result of which is that some audience members find themselves in a trance-like state and standing, whilst the rest of the audience blinks in the light and wonders what on earth just happened.
You cannot take part in this section of the show if you are a) depressive, b) drunk, c) prone to seizures or d) under 18. Interesting what strange restrictions youth brings. As a 17 year old you could pass your driving test at 2pm that day and have driven on the motorway at 70mph at 2.15pm to the Apollo, but then you would not have been able to take part in a large section of the show when you got there.