At YAPC::NA this year Matt and Mark will be sporting a limited run t-shirt, with only five shirts like it in existence.
The image on the shirt is a jocular composition of YAPC::Lego. This flippancy is a response to the YAPC 2012 organisers using a to-scale version of a velociraptor below a cow. Though the image they used was not that of a real Velociraptor but the Perl 5 version that is based upon the Utah Raptors, had they wished to be accurate they would have had to re-draw the image.
We at Shadowcat thought it was a funky challenge, the organisers clearly were playing with the real-world scale of a velociraptor, if not a real world representation, so we used a Lego scaled velociraptor, mini-figure and cow that Mark sourced at various Lego events to give a bold reply.
Three shirts will be available at the conference and awarded at Mark's discretion. There is also a limited run of the art cards and you can view the actual Lego pieces sourced for the image.
We know the organisers will take this whimsy in the tongue in cheek manner in which they used their take on the Perl 5 'unofficial' logo that we like to use.