Given that one is smoking pot, just what is in any way exacerbating about going about the business of ingesting TCH efficiently? I don't get that one at all. Thus to me this story is a great big fat zero.
The in government but didn't inhale means that Mittens is claiming that he did not acquire a government bureaucratic mentality, or think once in, it was better and more efficient, and more efficacious than he thought. It was nothing about well, inhaling pot, but rather about inhaling government.
Ok, so it makes some sense. It's just a terrible, terrible joke.