I did the postcard for this year's BroNYcon! I got pretty much free reign over it, so it was promptly invaded by a team of cuddly rainbow ninjas. Hooray!
(Just to be clear, the printed version did not, of course, have the giant watermark. :])
eta: Please do not use this for anything. This was specifically for BroNYcon and I would prefer it if people did not remove the text/watermark and use it for other things. Thank you.