Paint a t-shirt. Free hand paint it, or make a stencil.
Here’s how to make a stencil:
(1) method using curtain panels: http://modpodgerocksblog.com/2009/11/i-finally-screen-printed-with-mod-podge.html
(2) method using pantyhose: http://mycalicoskies.blogspot.com/2012/04/52-week-challenge-10-diy-screenprint.html
I would recommend a modified version of the curtain panels method. Curtain panels are much easier to fit over the embroidery hoops than pantyhose, but you’ll have to be much more gentler when applying the Mod Podge. I would also recommend NOT using the Fabric Mod Podge. Use regular matte Mod Podge; it’s smoother and easier to apply.