An explosive device. A booby trap. A package bomb. A hand-tossed grenade.
Long before George Harrison, Sean Penn and Madonna and the movie they made by that name, a Shanghai Surprise was a home made bomb used by the Chinese tongs or gangs. The expression probably dates from the late 19th or early 20th century. While I cannot cite chapter and verse of it's origin, I'm older than Madonna and understood the expression at the time the movie was made. Not everything is about sex, kids. That's why I unsubscribed from the UD.