Lutefisk is a Norwegian dish made from dried white fish cured in lye. It’s a dish that is served here in Minnesota. The joke is about the need for a lutefisk hotline (cause why would anyone need lutefisk that badly?) and the idea that they might sell out. Plus the implied accents.

Lsen -> “Listen [,]”

OlsenFish -> “I’ll send fish”

Edit: No, it’s just the OlsenFish. The “Lsen” I thought I saw at the top was part of “Olsen”, my vision failed me again >_<