My favourite
is the signs in shops which say "Sale! Up to 50%".

I challenged a bookshop sales droid one day and maintained that this meant that they should be selling everything for less than half price. He countered that the sign actually meant 'up to 50% off' but of course it didn't say that.

Since then however, I've noticed that shops do now include the word 'off', albeit in quite small letters usually. So it looks like there are more pedants going around...
( K2k6 has a proper job these days, Tue 12 May 2009, 9:18, Reply)