My sister does Know-Your-Customer stuff for a large company

Had dinner with her tonight and she said that one of her bosses had been grinning more than usual when giving her some files to check and everyone she phoned to check up on them with had been giggling

There was one common theme to the files and I couldn't stop giggling when I heard it

All the companies were based in Bielefeld

Yep, that joke's still going strong after 25 years