[Thanks to TidBITS.]One Apple geek tee-shirt feature the old-timey bomb symbol that Macs showed before OS X to hint that your computer had gone belly-up.
Apart from the (in retrospect) morbidity of the symbol, I find it amusing that you will not be allowed to board an airplane in an American airport if you are wearing this tee-shirt visibly. Seriously. Admittedly that's not a confirmed fact, it's an educated guess based on what kind of shirts people have been blocked for wearing. I know I wouldn't try it, these people have no sense of humor.