You have to pick:

You would almost definitely die from the fumes if you fell in a vat of rubbing alcohol

I'm not sure the fumes would be that big a problem. I'd be more concerned about simply drowning. Rubbing alcohol has less density than water so it'd be harder to stay afloat in. I guess it depends how deep the vat is.

Oh, it would also wreck my cell phone and watch and probably some of the other stuff I've got in my wallet. So danger aside, some of the other vats to fall into would be less expensive as well.

Rubbing alcohol fumes from even a small amount can be pretty intense. They may not be very poisonous, but you might pass out - and then its game over man. Game over.

you would definately die from the COCKROACHES if you fell into vat of cockroaches

Damned if I do, damned if I don't.

Alcohol would be quick and mostly painless though, cockroaches would be slow and painful.

I think the roaches would be too busy frantically trying to get out of the vat and away from you to do any nibbling. They're scavengers, they flee from anything that could be a threat.

It would still be quite disgusting, of course.