PHP has its own treasure chest of classic mistakes that surprises even the most seasoned expert: code that dies just by changing its namespace, strpos() that fails to find strings or arrays that changes without touching them. Do that get on your nerves too? Let's make a list of them, so we can always teach them to the new guys, spot them during code reviews and kick them out of our code once and for all. Come on, you're not frightening us!