I'm going to move my roommate's clothes from the washing machine to the dryer.
Why do you need to move his clothes?
No, I'm going to do it before he comes back. I'll tell him that I've already done it.
I'm sure that you mean well and want to help you roommate, but I would make sure you have a go signal before doing so as he may not be comfortable with you touching his clothes.
Nah I'm going to do it because I want to annoy him.
Well then I do not think that I would recommend you doing that. If he retaliates and messes up your clothes too, you may end up with a toxic living arrangement and you wouldn't want to live with him anymore. I suggest you just clean up after yourself and just do not touch his stuff as I am sure you don't want your stuff to be touch either, right?