Can you return an item after you wash it?

I ordered a shirt online, but they sent me the shirt in the wrong size. It was supposed to be a present for my boyfriend for his birthday, but he is picky about his shirt sizes. The thing is, I'm going to a concert tomorrow and want to wear the shirt. I know I will be getting sweaty and gross and if I wear the shirt I will have to wash it. My question is can I wear the shirt, wash it, and still send it back to the company?