One meaning behind the image of the skull is 'memento mori' Latin for 'remember you must die'. For me it's a reminder to live life while you can. Plus they look pretty fucking cool.
Bollox. Memento Mori used to be a top 10 World of Warcraft raiding guild, bet it was in tribute to them. Once they disbanded, you had to find new meaning.

Watching the world cup, at gym or even just on beach the latest trend seems to be these stupid stars. Just plain old 5 point stars any dickhead could draw, often around elbows. Why? Fucking morons.