From what I read about Korea, there is a snack company there that makes a wafer like edible stick that is dipped in chocolate. It is call Pepero and since the snack is a straight narrow cylinder like food it reminds people of the number one.
So some clever Pepero person came up with 11-11 (November 11th) is Pepero day and Koreans go out and buy this snack. See image of it here: http://twitter.com/SweetAndTastyTV/status/267719894479552513/photo/1
I was at Wal-Mart on 11-11-2012 and could not find this snack but I did find one called Pocky in the Asian food section. See image.