If you’re looking for an outrageous night out with a gang of mates Riverside Studios is offering a special cut-price rate for the Edinburgh Fringe hit: 666. If you can get together 10 or more people, ring the Box Office on 020 8237 1111, quote 'Riverside Group Offer' and get all tickets for just £12.50 each. But this is not a show for the fainthearted and ‘audience participation’ seem to be the watchwords. Here are a few quotes from some Edinburgh reviews: “Ribald and riotous, this is what late-night fringe theatre should be about.” Sunday Herald; “The Mary Whitehouse-alikes, Daily Mail readers and any other knee-jerk reactionaries will be queuing up to condemn this as pornographic filth. And that's pretty much all the recommendation you need.” The List; “Yes it's brutal, plumbing new depths of audience humiliation. But the fact remains that my cheek muscles haven't felt so sore from laughter of the Oh-my-God-I can't-believe-what-I-am-seeing variety for a long time.” Metro.