I read somewhere that nicotine decreases the half-life of caffeine in your system, allowing you to consume more caffeine and feel fewer effects from it.

This would explain the common trope of people smoking cigarettes and drinking coffee.

That being said, this is pulled out of my memory and I would have to spend quite a while trying to find any evidence of it, although everybody I know that smokes are consumes nicotine also consumes quite a bit of caffeine.