Stil I saw these exact same shirts yesterday here in Hangzhou. I wish I had the wherewithal to get a pic.
Going back more than 10 years, a young female teacher at my university in Shanghai wore a very similar T shirt. I asked her about the, erm, plant on the front. She had no idea.
Pervert, marijuana, whatever. They generally have no idea.
Luckily Stil is a highly principled man.