vegan
Explanation
The Joke
The comic features a conversation between several people about veganism. One person declares, "I don't eat any creature that feels pain." Another responds, "I'm a positive vegan -- I don't just oppose things, I'm in favor of pleasure." The first person asks, "So you're just a negative vegan?" prompting the reply "Yah."
A third person chimes in, calling the conversation "a creepy thing to bring up at brunch," noting that this discussion is "functionally unusual." The positive vegan then explains: "I break it into factions and am functionally unusual." The final punchline is: "Better and yet somehow so much worse."
The Humor
The comic satirizes the tendency of people with strong dietary ethics to subdivide themselves into increasingly specific and absurd philosophical categories. The joke is that once you start applying rigorous philosophical frameworks to food choices, you end up with bizarre distinctions like "positive vegan" versus "negative vegan" -- borrowing the language of political philosophy (positive vs. negative liberty) and applying it to dietary choices. The result is technically coherent but socially unbearable, which is why the observer notes it is simultaneously "better and yet somehow so much worse."
References
The "positive" vs. "negative" framing alludes to Isaiah Berlin's famous distinction between positive liberty (freedom to do something) and negative liberty (freedom from interference), applied here absurdly to veganism.