1
general::
Phrase(s): sleep with someone
1. to share a bed with someone. • Do I have to sleep with my little brother? • Many little boys have to sleep with their brothers. 2. Euph. to copulate with someone. • I hear Sam’s sleeping with Sally now. • Whom did you say he slept with?
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Be sexually intimate with, as in The playwright had made several attempts to sleep with the maid. The related phrase sleep together means "have sexual relations," as in We wondered if they were sleeping together but didn't dare to ask them. The verb sleep has been associated with sex since the 10th century. Sleep with dates from the 1300s; sleep together was first recorded a century later.
American Heritage Idioms