The pleasure/pain principle.

[slemslempike]

For the past few days I have been having really painful occasional anal spasms. This is probably easily explained by a combination of diet and citalopram, but the Muller Light adverts from a while back have had more effect on me than I thought, because all I can think is that, somewhere, someone is blithely having inadequately lubricated anal sex, and I am paying the price.