A linguistic theory of the Swedish chef:

Classically, the Swedish chef's language is defined by repeated "oo" sound e.g. "spoody hoody coocoonoot." Why?

Turns out one of the few vowel sounds that exists across Old Norse derived languages but is not present in modern English is "y" like the German ü or the French u in "tu." Pronounced by making an ee vowel with rounded lips. The foreignness of that sound leads to its emphasis in English speakers imitating any Nordic language.