To a German ear it sounds like pigeon milker...

I actually don't fancy this sport or hobby. You just have to pay attention the "feral" pigeons running about in the cities. Many of them have exactly one crippled leg, where their band originally was. After the pigeon doesn't return home, this thing cuts into the leg over time and in a slow and painful process the leg falls off...

pigeon milker would be the translation in Dutch, but perhaps it has a special meaning in Flemish...

"Pigeon milk" does exist: it is a type of crop milk, the regurgitated lining that parent birds feed to their young.

But "pigeon milker" as pigeon fancier instead is a copy of the Dutch word for nightjar ("geitenmelker"), according to NL Wikipedia:

https://nl.wikipedia.org/wiki/Duivenmelk

Nightjars were known once as goatsuckers in English because it was believed they sucked milk from goats.

So it seems it is just a play on words. I am not Dutch, though.