The "Vunter Sloush" song is a parody in mock German/Dutch of "Sinterklaas Kapoentje", a Sinterklaas (St Nickolaas/Santa Klaus) song dating back to the 19th century.
A loose translation of the South Park Slash version would be:
Wonder Slash Capon, Play something in my shoe, The wind blows Axel Rose, Thank you Wonder Slash
The Dutch in this episode isn't actually Dutch, it's German.
The way the kids react when they find out Slash isn't real is exactly how kids react about Santa Claus.
Kenny did not appear in this episode.
In one of the scenes in the episode, there is a computer with the wordBell on it, obviously a pun on Dell, a computer technology corporation.
The Slash song is based on a Dutch song "Sinterklaas kapoentje" a children's song about Saint Nicolaas. A Christian saint who gave to the children (and evolved into Santa Claus in the USA). Telling children that he is not real is about the same as the Slash moment in the show.