to be [a few bricks short of a full load, a few cards shy of a full deck, a few grapes
short of a bunch, one fry shy of a Happy Meal, a few sodas short of a six-pack]
Contexto
“But how would he have known what he was looking for?” Harry
asked. “He was a nice fellow, but we all know he was a few sandwiches short of a picnic.”