A former co:worker friend just asked me that, when she saw a pair of earrings I had just made.
For me, skulls never really meant all that much, until I learned about Dios de los Muertos (Day of the Dead).
I think of my grandmother all the time. The idea of a special day to honor our deceased relatives therefore allows me to pay a special homage to her. She also made me believe in some "weird" possibilities. If ANYONE could visit me from the dead, it was my Mimi. I dream about her all the time.
So, now I think of Mimi when I see skulls! Besides, Day of Dead artistry is SO pretty & colorful. I just LOVE that!