Pretty funny what Google AI says about the slang word "keff":

"Keff" is a Swedish slang word that generally means "bad," "crappy," or "uncool." It's used as an adjective and can be applied to anything considered undesirable or of poor quality. Interestingly, the word has its roots in Arabic, where it has a positive meaning related to goodness or fun. This inversion of meaning is similar to other slang terms that have developed in different contexts.

#keff