Jez Moonbeam thinks that his big pocket is the gateway to another dimension. This is obviously a load of grotty old nonsense, but you have to humour these people. He then asks us for a volunteer to be his first interdimensional test pilot, and explains that he would go himself but he has an appointment to get his eyes tested tomorrow, and he can't guarantee that they will have a branch of Specsavers on another plane of existence.
He looks at us expectantly. There are no volunteers. He then offers half a Kit Kat and a bag of pickled onion Monster Munch, and I immediately stick up my hand. I'm no mug - you've just got to hold your nerve and wait for the right offer. He takes me to a special fitting room, where I am kitted out for the journey. I am put in a special "dimension suit" which will protect me on the journey through the interdimensional void. It looks like a giraffe onesie to me, but Professor Moonbeam assures me that it is actually a very specialised protective suit and that the fluffy horns on top are designed to short out the nul-reality zone differential in the interstitial void. That, and they will also receive Radio 2, so I can listen to Popmaster on the journey. I am also given a lunchbox full of cheese crackers and a spoon, in case of emergencies. I am then shown into the giant pocket, strapped firmly to the lining and left in the dark.