I actually have a shirt like this

This one is dual-licensed under the CC BY-SA 4.0 and LGPLv3+
I'm starting to worry about DRM and Section 1201 of the DMCA so I chose not to license it under the LGPLv2.1 with this one

GIMP XCF
http://thepouar.dnsdojo.com/pouar/downloads/fursonatshirt.xcf.xz

High Res png
http://thepouar.dnsdojo.com/pouar/downloads/fursonatshirt2.png