People using 'less' when they should be using 'fewer'
EDIT: you guys have dug up some truly horrible pisstakes :D Thank you for those.
To the serious folk - relax a little. This is Mildly Infuriating, not I'm dying if this doesn't stop. As a non-native speaker I was taught a certain way to use the language. The rules were not written down by me, nor the teachers - it was done by the native folk. Peace!
Ok so, as a native English speaker, let me inform you, that whatever you think is a rule in English, isn't. It's a guideline. It's a hard language because we lack structure. The native teachers are teaching you the basic guidelines, not actual conversational English, which varies heavily on location, and social group.