Johnny Fallon

The face you make on your first Guinness is involuntary. The stuff is roughly 7x more bitter than Bud Light, and bitterness happens to be the one taste humans evolved specifically to spit out. Here's what's going on. Guinness gets its color from barley roasted at around 230°C, which is coffee territory. To an untrained tongue it basically tastes like someone dumped espresso in your beer. Then the nitrogen makes it worse. Guinness pours with a 75/25 nitrogen-to-CO2 mix, and nitrogen barely dissolves in liquid. Those tiny creamy bubbles everyone loves? That's the nitrogen. Problem is, nitrogen also kills the fizzy bite that takes the edge off bitterness in a regular beer, so all that roast hits your tongue with nothing in the way. Meanwhile your tongue carries 25 different types of bitter receptors, and their only job is detecting toxins. Light up enough of them at once and your body runs the rejection script whether you want it to or not. Pursed lips, little recoil, the exact face in this video. A psychologist named Paul Rozin coined a term for what happens after that first sip. Benign masochism. Humans are the only species that trains itself to enjoy things the body flags as dangerous, which is the whole story of chili, coffee, and stout. Takes around 8 to 10 tries before your brain connects the bitterness to the buzz and flips the signal from "spit this out" to "order another." So every Guinness drinker alive has made that face at some point, we just weren't on camera when it happened.