Would an electronic cigarette for cosplaying Sanji be acceptable? I don't intend to use it at all, just carry it around in my mouth.
If it's not actually in use, I don't see why it wouldn't be allowed. Since it's not creating smoke, after all.
I'm pretty sure it's OK to even use, since there is no danger for the users or people around you whatsoever. The ""smoke"" you exhale is just water vapor.
Alternatively, you can get those fake/joke cigarettes from Halloween stores that expel powder when you exhale into it. I'm sure those are much cheaper, but have less re-usability.