Afaik they can not inhale through gill splits, water flows only in through the mouth and out through the gills. So it should be 2, but the smoke would be coming out from the gills.

Are the gills like ears...?

I'm glad we have a scientific answer at last.

1. I saw it in a movie

I don't think you can smoke underwater

All philosophy is inherently existential in that something must exist to define philosophy to begin with.

Takes a drag of my cigarette and blows it out my gills

Surely thats a skill that would do well at parties. Like if we could blow smoke out of our ears

In the mouth, obviously, the most important part of wrangling the monsters in the darkness of existentialism is to do it with panache, and the second option is cooler.

The first option is like tucking a cig behind your ear. A viable backup.

It's more akin to using the tracheostomy hole.

Diver Dan proved it is number 2

This is all ignoring the fact that underwater the cigarette would not burn, hence there not being smoke in the first place.

Even with gills, the mouth is where they breath in

Just mix some phosphorus in with the tobacco

That is actually possible if you perforate your eardrum. Would not recommend it though.

In the butt I say.

Not with that attitude