three guys in a garage

count to three

Synonym of count to ten.

me three

Used to express agreement, after someone has already said "me too." Can be continued as "me four," "me five," and so on.

nice guys finish last

People who are decent, friendly, and agreeable tend to be unsuccessful because they are outmaneuvered or overwhelmed by others who are not so decent, friendly, or agreeable.

Three Musketeers

A group of three people who are very closely associated; a trio.

three score and ten

Seventy, being the number of years in a full lifetime of traditionally-expected duration.

three sheets to the wind

Unsteady from drink.

three skips of a louse

The worth of some trifling or insignificant matter; a whit or jot of value.

three squares

Three square meals, understood as a complete, satisfying, and nourishing regimen of food taken over the course of a day.