"Pop Guy" originally known as the "Ba Ba Ba Guy" is the nickname of a character in The First Guy To Ever Be A Toxic Fan, the 7th episode of The First Guy Series, portrayed by Ryan George. He is possibly referenced in The First Guy To Ever Make A Commercial with the character Frederick Noisemaker; the host of the show All The Noises I Know How To Make.
TFG6 - The First Guy To Ever Be A Toxic Fan
The "Pop Guy" is an individual who while standing in a field randomly made the sound "Ba Ba Ba..." His strange sound caught the attention of another unidentified individual wearing a bear t-shirt who liked it (constantly asking him to repeat the noise), and became a fan of his work, taking pictures of him and wearing a shirt which says "Ba Ba Ba Guy" on it.
He then makes a "pop" sound, with the toxic fan, preferring the old "Ba Ba Ba" sound, angrily claiming that he's changed and has to stay true to who he is, but after hearing it a few times, becomes a fan of the new "pop" sound, even changing his shirt to say "Pop Guy" on it.
Not long afterwards, a curious guy with a black t-shirt approaches them, and instantly becomes a fan after hearing the "pop" sound. Both fans start arguing with each other regarding who likes the "Pop" guy better, until they both ask him to write his name on their chest with permanent marker. The "Pop" guy gets exhausted, asking them to leave him alone and give him space.
The two toxic fans apologize, and Pop Guy apologizes after his outburst, claiming that he shouldn't turn his nose up at them for enjoying his noises, especially with how things in the world are at the moment. Surprisingly, this last bit angers the two fans, who tell him to stay out of politics and stick to what he knows. 
TFG21 and 36 - The First Guy to Ever Play Tag/ Duck, Duck, Goose
In "The First Guy to Ever Play Tag" and "The First Guy to Ever Play Duck, Duck, Goose" he can be seen in a background poster which promotes his new concert. The poster introduces him as "The Ba Ba Ba Guy" implying that he either got popular from the "Ba Ba Ba" sound or decided to stick with that alias over "The Pop Guy"
The Scary News Network
Most recently, the "Pop" guy appeared in The Scary News Network, it was said that people rumored that he was saying that the Scary News Network profits off of keeping their viewers scared and hopeless through sensationalist headlines. After this was rumored, Brett Newscaster, Peter and Gerald, being all demons, made him spontaneously combust, killing him.
- The First Guy To Ever Make A Commercial
- The First Guy To Ever Be A Toxic Fan