You posted this in "Restaurant Walkaround" so I strongly suggest you lose the flash paper.
Strict place you live in.
It's a legal nightmare, and not necessary. There are more factors to consider when working professionally than "what's cool".
Luckily, we don't seem to have a problem with it here...well...as far as I am aware.
It's not just cool though, it can be used as a nice opener if you do it right...or closer.
Either way, I wouldn't make a big deal of having it in your routine but if you have it and it's legal where you are, go for it.
If not, why bother? Use it on the street or in your own stage show if you were to expand into either of those fields.
Can't speak for the rest of the westerners but in Wyoming and Arizona you can still get a plate of "Flaming Fajitas" at any decent Mexican restaurant. That's a bit more of a fire hazard than a tab of flash paper.