What happened in "What Happens Next?"?

[Boober_Gorg]

I've seen this sketch numerous times, but all I remember of it is the theme tune, as sung by Gordon:

Do you know what's going to happen next?
Do you think that you can tell?
If you know what's going to happen next,
Then tell me before I ring the bell,
Before I ring this Dinger's ding-dong bell!