Not sure if that can fit on the t-shirt, but here are couple of ideas http://farm3.static.flickr.com/2174/2268237733_cda4a1dbb3.jpg http://farm3.static.flickr.

Not sure if that can fit on the t-shirt, but here are couple of ideas http://farm3.static.flickr.com/2174/2268237733_cda4a1dbb3.jpg http://farm3.static.flickr.com/2174/2268237733_cda4a1dbb3.jp... http://geektech.geektech.netdna-cdn.com/wp-content/uploads/2010/06/719a20f3a2e4.jpg http://geektech.geektech.netdna-cdn.com/wp-content/uploads/2... (these are 'captchas' that require you to solve a problem) Also, liked these (unrelated to maths): http://geektechnica.com/2010/06/10-craziest-captchas-out-there/ http://geektechnica.com/2010/06/10-craziest-captchas-out-the...