I read it in an interview with Jon in the Mirror (UK newspaper) suppliment ealier this year. I still have it.

What's the oddest thing that you've had lobbed on stage?

We played Donnington in '85 and somebody threw a pig's head on stage. Imagine that guy quietly queuing up for hours with a f***ing pig's head in his bag! We've had the usual bottles of piss thrown. The rule is never to throw them back or else they return tenfold. We learnt the hard way