This image has been making the rounds on the Japanese internet recently under the billing "The font that [only] Japanese people can't read." It's written in the font Electroharmonix (by Typodermic Fonts, apparently) which repurposes katakana and katakanaic bits into English letters. Apparently, the result is that it really is difficult to read for Japanese people (or "people whose 'mother script' is Japanese," I suppose).

Although I only have an unscientific sample of a few people I know personally, it sounds from their anecdotal reports that it's like trying to force one of those convex/concave optical illusions to pop the other way — you know you should be able to interpret the shapes differently, but by the time the image passes through the vision-processing part of your brain and into your conscious control, it's already too late to do anything about it.