@sundogplanets "Je moet geen oude koeien uit de sloot halen," Rough translation: don't rescue an old cow from a ditch.
Basically it means that you should not bring up old grievances in current discussions.
@sundogplanets We have a bunch of dairy-related ones also:
"Zich de kaas niet van het brood laten eten." Rough translation: not letting anyone eat the cheese off of their sandwich. Means that you can stand up for yourself and don't let people mess with you or treat you unfairly.
"Er geen kaas van gegeten hebben." Rough translation: [that person] hasn't eaten cheese from there. Meaning that they don't know what they're talking about.
"Huisjesmelker." Literally: house milker. Our word for landlords who exploit tenants by having many bad apartments that they ask too much money for, especially if they themselves don't have a "proper" job.
Similarly "uitmelken" implies milking a cow until nothing is left, with the obvious meaning.