Justin said he was familiar with Tattoosday because I had previously featured work by his friend Erick Lynch at Redemption Tattoo. He was likely referring to this post.
This work on his sleeve is based on the work of M.C. Escher. The tattoo artist responsible is Chris Dingwell, whose amazing work has appeared previously on Tattoosday here.
Thanks to Justin for sharing his work with us here on Tattoosday!