You ran out of cabinet space in your brain and because it's files are all crammed up with nonesense, you have no room for important stuff.

Because when you are trying to remember something, the thing you are most concerned about is not forgetting, so you say to yourself "don`t forget to....", "Don`t forget" "Don`t forget" "Don`t forget" "Don`t forget" "Don`t forget" "I have to remember to......what did I have to remember, all I remember is that I had to remember something, however I forgot what I had to remember."

you should know your dad`s birthday, and if you don`t and he gets pissed, tell him he`s the one who passed on the bad memory gene, so he can`t blame you