six and two threes

beast with two backs

Two people united in sexual intercourse in the missionary position.

deep six

To discard, get rid of, or cancel; to completely put an end to something.

eat for two

To be pregnant

fall between two stools

To fit into neither of two categories and, hence, be neglected or fail.

feed two birds with one scone

Synonym of kill two birds with one stone.

for two pins

Readily, with only the slightest encouragement.

greater of two evils

The most harmful or unpleasant of two undesirable alternatives.

hit someone for six

To affect in a devastating way by some unexpected news.