A task requiring extreme intelligence, skill, or competence, usually used in a negative or rhetorical manner to indicate the opposite. Just follow the directions as they're written—it isn't brain surgery.

Battlefield surgery that is performed hastily so as to quickly stabilize a patient and prevent imminent death. Popularized (and possibly coined) by H. Richard Hornberger in his semi-autobiographical novel M*A*S*H, which focused on doctors serving in a fictional mobile army surgical hospital during the Korean War. Primarily heard in US. At the height of the conflict, our surgeons were primarily concerned with meatball surgery, getting wounded soldiers patched up long enough to receive more specialized treatment down the line.

In the act of performing or receiving a surgical procedure. Dr. Miller is in surgery right now, but I can page another doctor for you. No, Mom's still in surgery, and I'm starting to get worried that it's taking so long.