You wanna know what really piffs me off? When someone asks me if I'm sure about doing something I am already in the process of doing. You know what bothers me more? When a computer asks me if I'm sure! Yes, I'm sure!
I'm deleting a file...and it wants to know if I'm sure. Well, yeah, kinda. I wouldn't have pressed the "delete a file" button if really I was looking to press the 'my computer is retarded' button instead.
When would an "are you sure you want to perform this action?" button come in handy???
"Are you sure you would like to launch a nuclear attack?"
"Are you sure you want to drink that much tequila?"
"Do you really think that those neon yellow pants are slimming?"
"Would dancing around on the table at a work Christmas party with nothing but a bra, panties and your boss' tie around your head be a good idea?"
Things like that would be useful in life. But, "are you sure you want to delete this file?"....not helpful.