Ricky Gervais` surprise appearance on Jimmy Fallon

Gervais, not listed as a guest, came out of the curtain while Fallon was making his opening monologue and could be heard saying to someone, 'Sorry, I'll be one minute.'

He then told the host, 'I can't do the show. I've got a thing I've got to get to, but I don't really like to go a day without plugging something, because I can't sleep.

'So it's The Office box-set - it's not out yet, it's not out for ages but I won't be here - it's the 10th anniversary of the office. This is out in November but this is out for download on iTunes for the first time, one the 24th of October.'

He then asked for the date to be lit up in flashing lights across the screen and got Fallon to hold the DVD box so it could be clearly seen.

At the end of his joke plug, he then lingered behind watching Fallon and ran back up to critique his performance.

'You're out here dying so just go for it,' he suggested. 'Do it again, and do it with a swagger - do it like you deserve this show.'