If you're like me and run through a full jar of peanut butter every week, this is kind of frightening. Apparently, you can make a jar of peanut butter glow in the dark using a laser pointer. Don't worry, your peanut butter is not one of those glowing nuclear rods that occasionally appear in The Simpsons — after briefly shining a blue or violet laser pointer on your peanutty goo (sorry, that sounds gross), your peanut butter will glow green due to something called delayed fluorescence, or afterglow.
It has nothing to do with how natural (or unnatural) your peanut butter is — it's caused by a light-absorbing material called a phenol. No, it's not something in the jar itself; if you take a spoonful of peanut butter outside the jar and do this experiment, it does the same thing. When nuts like peanuts, cashews, and almonds are heated crushed into nut butter, the phenol's effect is heightened. It's the same process that causes those glow-in-the-dark stars you had on your bedroom ceiling as a kid to light up, but cooler, since this is, like, something you eat.
See how it works in this NurdRage video (enjoy the alien-like robot voice it comes with):
Want to try it yourself to terrify guests at your Halloween party? As the video notes, any brand of peanut butter works for this, and you'll need a laser pointer because while any type of light can theoretically make peanut butter glow, you'll need something intense to make the effect very noticeable (blue or violet works best because they'll have the most light on the UV spectrum, which the phenols will absorb). It also works well if you freeze a dab of the peanut butter, because freezing heightens the fluorescent effect and makes the glow last slightly longer. And, if you happen to have some liquid nitrogen handy (as, you know, one does), the effect is positively otherworldly, as the video shows. According to The Nerdist, you can also try it with dry ice (you know, that fog-creating stuff you keep around for your haunted house, or whenever someone gets drunk at your apartment and sings "Total Eclipse of the Heart").
So there you have it: peanut butter can do pretty much anything. And laser pointers are good for things besides gleefully tormenting your cat. Who would have thought?