brose
Explanation
The Joke
A character shares a "life-changing vocabulary tip": in Scots, "brose" is an old term for porridge. In the next panel, we see them excitedly eating a bowl of "brose," only for another character to ask, "Why are you eating oatmeal in your underwear?" The response: "Because I'm eating BROSE!"
The joke is that learning a fancy or archaic word for a mundane thing does not actually change the thing itself. The character treats the discovery of the word "brose" as transformative, as though renaming porridge somehow elevates the experience, when in reality they are still just eating oatmeal in their underwear.
The Humor
The humor comes from the gap between the character's enthusiasm and the reality of the situation. The phrase "life-changing vocabulary tip" sets up an expectation of something profound, but the payoff is simply a synonym for porridge. The character's behavior has not changed at all -- they are still doing the same slightly undignified thing -- but they feel elevated because they have a new word for it.
This satirizes a common internet phenomenon: the "life hack" or "mind-blowing fact" that is really just trivial repackaging. It also plays on how people sometimes use obscure or foreign terminology to make ordinary activities sound more sophisticated (like calling a nap a "siesta" or a walk a "constitutional"). SMBC frequently mines humor from the human tendency to confuse linguistic novelty with actual substance.