IDIOM ►

throw in the towel (or sponge)

Meaning 1
the boxing manager throws in the towel to stop the fight
Sentence 1
His manager threw in the towel and the fight was over.
Meaning 2
to give up, to not pursue an objective
Sentence 2
I want to throw in the towel on this marriage. It's not going to work. We fight too much.

Derivation

In the early days of boxing, opponents used bare fists to hit each other. When hit a sponge was used to wipe away blood. When a fighter was no longer able to fight, his manager would throw the bloody sponge into the ring to stop the fight.