As it turns out, this is the same sign that was used in the famous internet meme, "All Your Base are Belong to Us" (known as AYB or AYBABTU). The original shot of the sign, here, was turned into this sign, here.
All Your Base website.
All Your Base flash video.
All Your Base at Know Your Meme.
All Your Base at Uncyclopedia.
All Your Base video on YouTube:
I recommend watching the flash video, it seems a bit clearer.
The sign, and its partner on the westbound lane of I-94 (Google Street View), is also a bit of a meme in and of itself, having been posted on at least a couple blogs, and mentioned or linked to in threads about strange signs and strange placenames in the U.S. and around the world. Get your Bad Route Road e-card here!