Joke: these letters are on the front of a business in Turku. I'm not sure what sort of business they do.
Joke: JoLKa (i.e. Russian for spruce). In Finnish, 'spruce' is kuusi, which is homophonous with the number six in the nominative. I would often joke with people about setting up a "jouluviisi" instead of a "joulukuusi", and such.
Joke: IBC is a brand of root beer. If you account for voicing and interpret the <i> as a consonant, you can get to J-P-K.
It's not clear exactly where the umlaut came from, but there may have been a suffix at some point that was lost, or the initial /j/ may have influenced the vowel quality in this very common lexical item. The pattern itself is also obscure.
Joke: JuST, as in "just one".