PC: So I'm completely behind the wall, total cover?
DM: Yes.
PC: And I'm not in anyone's line of sight?
DM: Yes.
PC: But I can see the dragon's toe. Can it see me?
DM: No.
PC: Okay, I Hide.
DM: Roll.
PC: Okay! Aw, crap. 14.
DM: As you secure your position, you step on a twig, which...