Like all boys, I love cars. As a proud owner of a Mazda Miata, and an Autocross participant, I felt the need to publicize my passion with a shirt.
The solo-on logo is a parody of the snap-on logo. The meaning to be derived is that autocross cones used during Solo racing competitions are the tools needed to tighten the “nut” behind the wheel (make you a better driver). Becoming a better driver has long been said to be the most advantages modification you can do to any driver/car combo.