Throw in the towel, give up, give up a fight or task. The expression has no pugilistic but thermal origin. In the Roman public baths some powerful patricians stood in front of some beautiful young man. If the efebo made another knot to the towel he rejected the proposition. If I dropped it, I'd accept it. Not much has been discovered a Turkish bath in which Antinoo threw his towel at Emperor Hadrian. "Hic Antinous Hadriano linteum suum iactavit", reads the inscription.
