Flamingo Foot

This is a wordplay joke, my friend. The person's wife is saying they act like a flamingo. A flamingo stands on one leg, so the person then says they had to "put their foot down," meaning they had to be firm, but also plays on the flamingo's stance. You probably didn't know this, but flamingos are social birds; they live in groups called colonies or flocks that can number in the thousands.