Evolution.

May 2000. I can pinpoint the moment I came out down to the practical moment: I was at a Pride meeting at Illinois State to "see" if I was actually gay (heh), and the speaker that night was a biology professor who gave a talk on this very subject. I'm not a big fan of the punchline - ones like these are literal punchlines, in that there's no joke other than "I am going to hit/kill you now." It's a sign of a weak joke and you see it a lot on bad sitcoms.

Let me share a big cartooning mistake: those trees in the background, when you show the branch structure inside the outline that represents the leaf mass - that's how you do it when the trees are on fire. You don't show the branches when they are "normal." It's a who-cares kind of thing, but if you look at them, those trees in the background are clearly on fire. It makes the strip seem that much more surreal, I guess.