scratch for (one)self
To be self-sufficient. Now that you're a college student living on campus, you can't rely on your parents to take care of you—you need to scratch for yourself. I come from a big family, so I've been scratching for myself since I was a little kid.
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!