The phrase "throws sponge" is an idiom that means to give up or surrender. There are several synonyms for this expression that can be used interchangeably in order to convey the same meaning. Some common alternatives include "throws in the towel," "waves the white flag," "backs down," or "concedes defeat." Other similar phrases that can be used to describe giving up include "quits," "throws in the towel," "retires," "surrenders," and "cedes." Regardless of the terminology used, the implication is the same - the individual in question has given up and is no longer fighting or competing.