I've been musing on how part time work like playing music is described differently than other work. If you only perform occasionally, you're a "semi-pro" musician. So if you also moonlight at the local grocery store for extra money, are you also a "semi-pro" stock clerk?
"I mean, I could go pro, but you know how dog-eat-dog the stock clerk game is. I just like stocking shelves for the enjoyment, you know? You should check out my awesome collection of aprons some time."