WIY,
In Hebrew each word has a shoresh. The shorashim have a conceptual meaning that morphs into specific meaning depending on the context of the word’s use and prefixes and suffixes. So while “schok” can mean “laughter” it can also mean “play” (As in Shmuel II 2:14).
Maybe I am just out in left field here, but to me a word that can mean play and laughter can mean “fun” as well.
Writersoul,
I believe “kef” comes arabic.