The Radio 1 DJ was appearing on Soccer AM and hadn't realised his mic was still on.
Twenty famous faces will be put through their paces in the tent in aid of Stand Up To Cancer
Nick Grimshaw 'Absolutely Gutted' To Miss A Full Day Of Grueling Sport Relief Challenge On Doctors' Orders
The Radio 1 presenter is one of several stars currently on a 100-mile expedition across the desert.
The Radio 1 DJs are on the run again.
We're very excited to see what their front rooms look like.
Numbers for the whole station were down half a million on last year, though.
WE'RE STUCK AT WORK, THIS IS COMPLETELY UNFAIR.
Piers accused the band of "using sex to sell albums" in their new music video.
It is the first time since 2012 his figures have dropped below nine million.
Greg talked exclusively about his plans for the show and challenges in the industry.