Custom t-shirts can provide a unique alternative to standardized fare, but set the designer in yourself loose, and you'll likely end up with Che Guevara requesting "more cowbell". For a custom t-shirt that protects you from yourself, check out Zero Boutique.
100%-cotton proof of Nova Scotia's "More Than Just Lox!" touristry campaign, Zero's a design shop that offers a few sweet graphic options, then lets you spin 'em off into near-endless permutations. To start, pick from their sometimes fun/sometimes disturbing designs, including the current highlight: two space-helmeted suits exchanging a firm handshake (sign of confidence = making direct visor contact). Next, choose its American-Apparel-blank base (standard, longsleeve, baseball, and ringer) and color scheme; you get at least 12 options, or just enough to guarantee that the colorblind will pick pink.
Five graphics are always available, and new ones're swapped in every two weeks. If you miss the one you want, ask Zero to notify you when it becomes available again -- which'll be shortly before you finally liberate that Latin American country via the power of bovine percussion.