Pi on your face.

My son inspired this design. More about that here:
http://parisvega.com/2016/01/26/explaining-pi/

Pi = circumference divided by diameter. With the first 39 digits of pi you can estimate the circumference of every circle within the observable universe: 3.141592653589793238462643383279502884197

Buy it on a shirt here:
https://society6.com/product/pi-definition-1_t-shirt?curator=parisvega