• not to have a leg to stand on

• keep it dark

• build on sand

• ahead of behind on schedule

• have a head on one's shoulder

• a shot in the dark

• rain cats and dogs

• talk the hind leg off a donkey

• a shaggy-dog story

• donkey work

• bet one's bottom dollar

• the sixty-four thousand dollar question

• know which side the bread is buttered on

• from the year dot

• be sold on it

• what the doctor ordered

• tread on his corns

• bold on like grim death

• have one's head screwed on the right way

• in the dark

• a dark horse

• get started on it

• let sleeping dogs lie

• hard on his heels

• stand on ceremony

• dot one's I's and cross one's T's

• go to the dogs

• trade on it

• what's up doc

• be hard on

• not to darken his door