A prominent English grammar teacher at Fenerbahce High School in Istanbul, Turkey created a new meaning of shit down in the 1990's as defined below. Unfortunately, the English-speaking world has known nothing about this contribution. I am very proud to present it here as one of her students. Learn and widely use it, please.
shit down (v):
1) (order) to tell someone to sit down when they fail to answer a question properly.
2) fail to respond a question properly
You couldn't respond the question again. Shit down and next time work hard.