What are some cute ways to personalize a t-shirt?

I am working as a Jr. Helper at my church's VBS this week, and all the workers have to wear matching t-shirts so that the kids know who to follow. I want to try to personalize it a little, but it has to be appropriate for a kids church event. I was thinking I could maybe cut it or put ribbon or something, but I don't really know how to do it without ruining the shirt. Please post a link or some instructions as to how to do that. Thanks so much!