break your back
When someone is really good at sex and leaves you sore the next day
I can break your back girl
Break your back
Having sex with someone in the position of Doggystyle, resulting in the girl arching her back
I'm going to break your back
Step on a crack, break your mother's back
This is an old children's game, anyone who trod on the cracks between the paving stones was out, until only one player was left, he or she was then declared the winner.
Step on a crack, break your mother's back– Most of us know the old rhyme “Step on a crack, break your mother’s back.” Whether the rhyme is the cause of, or a result of, this superstition is uncertain, though belief in it persists in many people today, even if subconsciously. Come to think of it, avoiding sidewalk cracks is probably a good policy for anyone who wants to avoid tripping.