I've done quite a few very impatient "HELLO?!"s in my time, generally after a rapid succession of telemarketers and hangups that make me want to yank the cord out of the wall, but I don't think I've done a "WHAT?!" yet. Generally by the time I lose my patience, it's my mom or grandma or something calling, and I'd feel wretched if I greeted them with a "WHAT?!" So I try and keep it civil when answering. If I'm absolutely patienceless, I'll just not answer at all and think of the best way to simultaneously destroy all telephones in the world.