At first, this item looks like a gag gift, but it isn't really. It's just specific to the public transit commuter (like my sister, who rides the NYC subway every day).
Every devotee of public transportation has some interesting, often traumatic, often very funny story to tell about her crowded journey. Flashers, muggers, the unwashed, the insensitive, and the extremely noisy (and sometimes insane) all make an appearance on a daily public commute. And this t-shirt reminds public commuters to (in Japanese, no less) "Beware of Perverts." Such good advice, particularly for the ladies. Send this top to any hardcore commuting woman, and she will laugh and thank you (and maybe even wear it on the subway, scaring off Japanese tourists by the tour bus-full).
This reminder of the commuter's plight is available at www.thinkgeek.com. Order them as gifts and spread the awareness far and wide.