For instance.....about a month ago we were talking about age gaps in relationships (yes the age gap thread inspired me to write this) and my mate said 'oh yeah when travelling me and my mate came up with the best equation, you should half your age and plus 7'
so i reply 'oh no, that's been around for ages - everyone knows that one'
him: oh no we genuinely thought of it
me: no. no you didn't.
This also happens when some people claim they made up particular drinking rules.
Also, people who say 'The awkward moment when.....' anger me to the very core and that's one solid core guys