screw (one)self up to concert pitch
To prepare for any event or crisis that may occur. My dad is nervous about me driving so far on my own, so I'm sure he's screwed himself up to concert pitch and is stationed by the phone in case I call.
shit (one)self
1. rude slang Literally, to defecate while still wearing one's clothing. I need you to pull over the car right now, or else I'm going to shit myself!
2. rude slang By extension, to be very surprised. When I saw that the magazine had published my letter to the editor, I practically shit myself!