This you have to see to believe:
If you haven't run across these instruments before, they are called schalmei (or sometimes, confusingly, shawms). They work on the same principle as a bicycle horn, without the bulb. Most have valves, so that you can play several different notes (in a limited range). I believe there are some set up to play 3- or 4-note chords, while others provide bass notes (in the video you can see several made in a sousaphone wrap).
There are an amazing number of videos by this group alone (i.e., more than one ). I think the hats must be required by law...