Watching shows is so last summer. At this year's Edinburgh Festival Fringe, it's not enough simply to buy a ticket and settle back in your seat; you have to prepare to become part of the show, too. Interactivity is everywhere, from plays which train an unforgiving camera lens on the stalls, to stand-ups who make hapless audience members their shows' stars. Promenade theatre is a walk in the park compared with this, the new breed of ultra-experimental shows which make extraordinary demands on their audiences: asking them to dance for three hours non-stop; to leap into cars with strangers; even, in one case, to feed their hard-earned bank notes into a shredder.
Comedy is getting in on the act, too. The old stand-up's ruse of picking on a man in the front row and making fun of him is no longer enough. You have to dress him in green Lycra, stick him on a skateboard and slobber him with kisses, too. Joining in is now as much a part of the Fringe experience as queueing and rain.
And so, in the past two weeks in Edinburgh, I've signed up for a humiliating public piano lesson in What Remains, taken part in a windswept singalong of "The Bonnie Banks o Loch Lomond" from the top deck of a bus in The Tour Guide and performed a Cheryl Cole-inspired dance routine in Jessica Ransom's Unsung Heroes. I've obediently meditated (or tried to) when instructed in David Leddy's Untitled Love Story, acted as assistant clown on the Royal Mile in You Once Said Yes, and sung the chorus to a piece of performance poetry, playing a sub-par Dido to Luke Wright's Eminem. Why? Because, frankly, I didn't have a choice. And that's not to mention all the times I managed to avoid getting involved by shrinking back into my seat and looking firmly at the floor.
There were also opportunities to share the intimate secrets of my love life in Looser Women, to slow dance with sketch troupe Lady Garden to "Lady in Red", or act as a towel girl to the comedian Tim Key who performs half of his show in the bath.
Maybe the financial crisis is to blame – using a captive audience is cheaper than hiring a chorus line, after all. More likely, though, it's that performers and companies have realised how much audiences enjoy actively experiencing a show rather than just passively watching. And, so long as it's not you being picked on, it's enormously fun to watch.
Pantomimes have been working on that premise for years. Punchdrunk took up the baton, kicking off a new wave of promenade theatre where audiences walk through the performances and experience them individually. And, in the production of One Man, Two Guvnors at the National Theatre, James Corden pulls two stooges out of the audience to hilarious effect.
It's only the start of what is sure to be a trickle-down effect, bringing more extreme interactivity from the Fringe to the West End. In the meantime, then, audiences would do well to work on their wallflower technique: sit five or more rows back, right in the middle of a row and never, ever catch the performer's eye. You might just get away with it.