I googled the lyric when posted because I only have it from the contextless world of Instagram reels, and I have a fetish for accuracy.
It was indeed from Jon Lajoie, but not the song you link. It looks like he did a followup track called "Everyday Normal Guy 2" which includes exactly the loop you hear (with "motherfucker" and not "guy" in the refrain) everywhere on social media right now.
