(Vocabulary postings are words or phrases I recently came across in reading, did not fully understand, looked it up, and discovered something new.)
Sandbag: A slang verb, to hit (or be hit) severely and unexpectedly. Garrison Keillor recently used it, saying he was sandbagged last year with legal problems. The term is often used in connection with an athletic contest where a contestant hides their abilities, then sandbags the unsuspecting opponent. If the new contestant is brought in secretly just for the contest, they are called a ringer.