It's a reference to The Twilight Saga novels, which they completely butcher vampire lore and makes it so that when a vampire steps into sunlight, it glitters (yes, glitters). Edward Cullen (a "vampire") was one of the main characters.
In the movie Twilight, Edward, the main character, steps into the sunlight and sparkles.He's a vampire. This Will-O-The-Wisp is somewhat the same color and it sparkles.