Sesame Street has been educating children for generations. The storied television show is largely seen as revolutionary for putting diversity at the forefront of its mission and for modernizing early education in the 1970s. Today, the lessons children learn from the program expand beyond simple ABCs and 1-2-3s. It has made headlines in recent years for carving out a space to teach children about incarceration, autism and homelessness.

But here’s one thing parents probably never expected on Sesame Street’s curriculum: profanity.

The internet is back at it again in another of those “White/Gold vs Blue/Black Dress” phenomena. On Thursday, a parent on Reddit posted that he might have come across the new “Yanni v. Laurel” (another topic of internet debate) while watching Sesame Street with his daughter, Yahoo Entertainment first reported. In a clip featuring Spanish-speaking puppet Rosita and Grover, it appearsΒ the amiable blue Muppet dropped an “f-bomb.”

“Move the camera. Yes, yes! That sounds like an excellent idea,” Grover says to Rosita, who appears to be recording from a cellphone.

But that’s not what everyone hears. Instead, some people are hearing “Yes, yes! That’s a f—ing excellent idea.”

The confusion over what Grover is saying is amplified, of course, by context: Most people assume there’s no way Sesame Street would have Grover use profane language on television. But then again, others are open to contemplating the possibility.

It appears the source of a person’s audio might play into what they hear. While listening with headphones, Grover clearly does not use inappropriate language. Listen again on a cellphone from, for example, Twitter where the clip in question was trending Friday, and you might be shocked to hear profanity.

Even with all the talk on social media, the controversy has yet to be addressed on Sesame Street’s nor Grover’s official Twitter accounts.

To settle the discrepancy, one Twitter user suggested calling in a professional lip reader. Good one.