Some people express themselves with tattoos, so it's natural that a vegan or vegetarian might decide to display their philosophy on their skin with art and words.
Vegan and vegetarian tattoo art sometimes weaves in other aesthetic or belief systems: Christian, Buddhist, Anarchist, Animal Rights, Feminism, Punk, Rock and Roll, War Protest, Environmentalism, and even demonic realms.
Sometimes the vegan and vegetarian tattoos are very public access, other times they are more private.
Hard telling where a vegan/vegetarian tattoo might show up.
Imagination and body art.