What was the purpose of Eddie and Berko for that matter

To pose a couple of existential questions, and to get Mark the brownies for the Gwar scene, one of the best things in any film ever.

Berko and Deb had some kind of backstory, like they were in a relationship and had a falling out, hence the scene where he tells her, "I'm trying to say I'm sorry," or something to that effect

He also leads the band that sings "Sugarhigh" at the end

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she threw a pot at Precious and knocked up her head

I get why Berko was there, with the whole thing with Deb and all, and that he did a song for the movie, but Eddie, I have no idea why. Additional comedy, maybe? He was a pretty cool character.

In the Remix Special Fan Edition, there are a few scenes which show Eddy working in the corner of the store which deals with Vinyl Records. So it seems he works the vinyl section, and even works on reparing them.

Just watched it last night so it's fresh in my mind.

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Our Universe is ruled by random whim, inhabited by people who laugh at logic. -Dexter

Eddie was there because of the fight between digital (CD) & analog (Vinyl) in the 90s. He represented the old school just like the store in itself. Also as someone else pointed out him and Mark were close buds.

Berko played a major part @ the end because he actually still had a band. etc.