This is a matter of contract--if your friend did indeed sign a contract stating that he is responsible for the tuxedos, then yes, he can be held responsible for their nonreturn, even if it was a different person (i.e. you) who did not return it.The tuxedo place is doing nothing wrong--a tuxedo costs money, so if it is not returned, they are out money. They are not required to absorb a loss simply to avoid "botherin" your friend. Your friend chose to rent from them and chose to sign an agreement stating he would be responsible for the tuxedos, so pursuant to that voluntarily signed agreement, they are looking to him for compensation for the delayed return.