I am now 18, is it illegal for me to smoke with my underage friends?

So i'm 18 as of last week and over Christmas break my friends and I are going up to Tahoe, btw i live in California, and i was wondering if it is now illegal to smoke shisha (tobacco) product with my friends? They all have pieces and have their own shisha and hookahs but i was wondering if i can get fined or cited or arrested for smoking with them even if i don't buy for them? Thanks people!!