A Google and Wikipedia search turned up all sorts of interesting information about the sock glue, including a blog post about cosplay, which included a blurb about fashion model who was so skinny her pantyhose fell down while she was on the runway; the author suggested the model in question might have benefited from the use of this Japanese sock glue.
According to Wikipedia, during the late 1990s, a number of Japanese high school girls started wearing oversized socks with their uniforms. Originally, the socks were intended for use by hikers and mountain climbers; I assume it was pretty much a tube sock, but eventually a number of companies started manufacturing deliberately oversized socks specifically for export to Japan. Since these socks have cuffs that are wider than the average high school girl's leg, they're not likely to stay up without assistance of some kind, be it a garter or glue. Some clever person came up with the idea of using a glycerin- or water-based adhesive to do exactly that.
The fad caught on among younger students who wanted to imitate their older counterparts, and even the negative reaction by a number of school officials made the idea gain wider appeal... except among adults. Still, it's not hard to find sock glue on a number of websites catering to Japanophiles and cosplay culture.