“Someone had a Grade A lungfish decorate their home for a merry fool’s function.”

This line came from a Rick Perry endorsement ad audio-doctored by the brilliant dub artists at Bad Lip Reading. Remember Audio-Tune the News? Bad Lip Reading is like that, except they graft absurd voiceovers onto video clips of everyone from pop singers (Bruno Mars) to politicians (Obama)—none of them as hysterical as Perry’s sabotaged campaign ad, which went viral and gathered almost two million views.

BLR is aural graffiti at its most ingenious: An ardently gesturing Perry stands at a podium flanked by American flags and says, “The tax and spend and borrow agenda of this president led to the first ever downgrade of credit rating of the United States of America” and Bad Lip Reading dubs: “then I suspended Marcia off this bridge and took a virgin heifer night-riding for a while, we never got a dead spirit.”

You laugh because of the e.e. cummings-like whimsy of the diction, you laugh at the lazy attempt at a Texas accent, but you also laugh because of the strange visual effect that persuades you to believe, despite the absurdity of the audio, that Perry actually seems to be mouthing these incoherent, dream-like sentences.

As it turns out, this audio-visual trick, which convinces us that Perry went “night-riding with a virgin heifer,” has a name. It’s called the McGurk effect, after Harry McGurk, who in a 1976 article in Nature, asserted, while examining language development in toddlers, that speech perception is a multimodal endeavor, involving more than just our ears. The McGurk effect is essentially an optical illusion by which the visual stimulus overrides the aural perception of words (or even sounds). When a “bah” sound is dubbed over the video of a man making what is obviously a “fah” gesture with his lips, we don’t hear “bah”: we hear “fah.” It turns out we believe words with our eyes just as much as our ears.

Perhaps you’ve always been aware of something like the McGurk effect operating in your own life. For a certain portion of puberty, I became a kind of expert McGurker, my lip-reading skills honed in those precious hours after my parents and younger brother had gone off to bed. I’d mute the TV and turn the channel from a late night repeat of Sportscenter or the Discovery Channel to soft-core porn on Cinemax, holding my heavy breaths from time to time to make sure no floorboards were creaking upstairs. The images would come straggling in through thick rotating bands of cable static, but after a while they would hold. I’d see a leg, a nipple, a pouting set of lips seeming to mouth the words “Buck me!” as I McGurked into the wee hours.