When people don't care about others.
Oh and also:
When people say stuff like "I hate people who..."
It should be "I hate it WHEN people..."
E.g. instead of saying "I hate people who play music too loud" you should say "I hate it WHEN people play music too loud."
Because why should you hate someone because of one trivial thing?
Edited by Eternal Mametchi Fan, 31 July 2014 - 10:14 PM.