I wore the rsa-dolphin t-shirt all over the place and nobody batted an eye back then, but a dolphin made up of ASCII characters is quite a bit less obvious than the one you linked.
OpenBSD being based in Canada ships strong crypto, but has had a sometimes troubled relationship with certain regimes.
http://www.cypherspace.org/adam/uk-shirt.html
A t-shirt with a Perl script that implemented RSA encryption strong enough to be technically illegal to export from the US.
(I must sadly admit to being too cowardly/sensible to have taken that shirt to the US in the late 90s...)