I've been acquainted with two folks who lost their tempers more easily after smoking. The vast majority of others have all been more mellow in response.

Cannabis works on both excitatory and inhibitory nerve signals, affecting neurotransmitters that help send and receive those signals in several ways. And it works differently in different people. Then, of course, different strains affect people differently, too. It makes sense to me that, because it has lots of different types of actions, what could mellow 8 people out of 10 might unleash the less-than-mellow side of the remaining 2 (or however many). Other drugs can do the same thing.

I'm betting it's like PB said. It just unleashes his inner butthole tendencies as it works its unique "magic" in his brain, probably lowering his inhibitions. I believe I'd gravitate toward other friends to smoke with!