Yeah I was about to explain that one about the lipstick..
"Why is it that doctors call what they do "practice"?"
Because in a way, they are learning all the time.
"Why don't you ever see the headline "Psychic Wins Lottery"?"
Because real phychics don't exist?
Well I don't think they could in that way. I think if they could, it'd be reading peoples minds, but no one would know yet.
"Why is it considered necessary to nail down the lid of a coffin?"
Could be something to do with tradition to mean something more than nailing it down: