Hang On!
Synopsis
Essentially a live radio-quiz-on-the-telly, kids would phone in and brave three questions and Pat Sharp's current haircut/shirt and if they succeed then they win a prize. To make things even simpler, if one caller gets it wrong, the next caller would get the same question.
This was the ultimate in cheap TV except that the prizes they gave away were actually rather good. Once during each fifteen minute episode an alarm would ring, meaning that the next prize would be actually rather cool (a holiday somewhere or something). Other prizes included Discmans, consoles, that sort of thing. Prizes could also be won if you spotted the 'deliberate mistake' which would be revealed in the next episode.
We're not quite sure what was going on in the screens in the background, though.