The "heavy mental" catchphrase with an artistic twist.
I remember reading Terry Pratchett's "Johnny and the Bomb" as a kid, and Bigmac was wearing a "Heavy mental" t-shirt. I've wanted such a t-shirt ever since, and now I finally made the design.
By the way, those strange things hovering around the brain are (supposedly) neurons. :P
You can buy the t-shirt on:
• RedBubble (available on phone cases as well)