But would you call muggins on a child?

Signs you're in a diner in rural New Hampshire-- the daily special is "boiled dinner" with no elaboration required, and under the counter you spy a cribbage board and deck of cards for the slow times.

For those unfamiliar with the game of cribbage, one of the quirks is that if your opponent fails to correctly count up all the points in his hand, once he has moved his scoring pegs, you can then announce the missed points and claim them for yourself. This is called muggins. My mother was famous for calling muggins on her own children-- once we were old enough to play the game, we were old enough to play it cut-throat style.