How would one make a bike louder, but only temporarily?

I've got a pretty quiet bike, a Yamaha Fz6, and for reasons I won't get into because I know it's an unpopular opinion, I like having a quiet bike. However I just moved to California and I can definitely see (and also hear) the advantages of having loud bike. So rather than downshifting/higher RPMs, is there something I can use, do, or add mid-trip to make my bike more audible? Perhaps I should get a real loud speaker and play "vroom vroom" noises on it (I'm half joking, but is it doable?) via /r/motorcycles https://www.reddit.com/r/motorcycles/comments/f3r2sy/how_would_one_make_a_bike_louder_but_only/?utm_source=ifttt