The Rats tearing up the Travolta posters is one of the all time highlights of TOTP for me.
During the October half term school holidays in 1978 my mum said she would take both my sisters and myself to see Grease at a major cinema in Newcastle. I opted out and was given a pound instead - some of which I used to buy 'Rat Trap'. I still think I made the right choice... and when I saw the Rats rip up those posters a few weeks later I was over the moon
Personally I found it rather childish.