I've been unable to figure out which year it was made, but I know the artist ("Eddie Meduza") and the name of the song ("Åh! en sån lyrik"). It was re-released on the album "Alla tiders fyllekalas. vol 14" after his death (he died in 2002), so that's not when it was originally released/made, but somebody searching for the song might be fooled into thinking that, so I'm mentioning it here.
It's one of his "joke songs", and he sounds clearly grown up in the lyrics (which aren't heard in my sample), which means it was definitely later than 1980. That much can be established. It might even be that this was one of the last songs he made, right before he passed away, but I would guess that this was made in the mid-1990s or maybe early 1990s. It doesn't really matter. It was made after 1980 for sure.
I've heard an American song from (presumably) the 1960s or maybe 1950s (but could in theory be from much later) which has almost the same tune, albeit played faster and slightly differently. I have no idea what that song is called, but I've been searching for it for a long time.
When he didn't make obvious covers on English-language songs, this guy (who I admire) usually had a very unique sound and was very creative, so it surprises me that he would just "steal" a tune like this, if that really is the case. I hope it's not. It may be a case of him having heard it at some point and forgotten that it existed, and then later genuinely thought that he had come up with this "original" sound without intending to steal it from anyone. It could also be that I've got this all wrong and that the American song actually was made after his, and the exact reverse situation is the truth... but I frankly doubt it. It's probably just wishful thinking from me, as a fan.
Either way, it would be extremely interesting to hear the "original" song and also to learn whether or not this would be considered a copyright violation/musical theft. And also if this kind of thing is common to happen by accident.
Here's the section I'm particularly interested in: https://vocaroo.com/embed/jBniJcPuyqx (Whether stolen or not, I like the sound.)