Does one of your shirts have "Mohammad" written on it? I think we should refrain from any kind of islamic art which may have the potential of becoming a source of disrepect. For example if this shirt has "Mohammad" written on it or any Quranic verse then people washing dirty clothes with it can be a wrong thing to do; also water from such washings goes to the drain; and not to forget people can wear these while going to the wash room. Point is i just wanted to bring this to your attention that these things can be a source of potential disrespect and as muslims I am sure that is something one would not want to have contributed to, in any way.