I was wearing blue sweat pants when I went out to day and he went after me. The last time he went for me was when I brought the new blue heated bucket in the coop. He is the dominant roo and usually leaves me alone not sure what is going on..
I don't know about blue, but I've had experiences of Jungle fowl that hated yellow.
When I was a teenager, I was a Zoological Explorer Scout, and worked at the Seneca Park Zoo, in Rochester Ny. They had Jungle fowl running around the area where the large hoofed animals were kept. They were completely peaceful, benign birds until I put on the yellow work boots we used before cleaning the enclosures. Those yellow boots sent the roos into a rage! I'd be raking and hear the slap, slap, slap, of angry little chicken feet running up behind me. They would jump up and try to sink their spurs into my upper legs! Take off the boots, and they went back to being calm, serene birds!
I think maybe that the yellow boots mimicked the bright yellow of another rooster's legs, and triggered aggression. At least that is my theory. Is your roo an Ameraucana or EE? The have blue legs, so maybe he has the same issue?
I was thinkin mine doesn't like red?? When I wore red, he went after me. Actualy I think it's spring time. My roo is acting strange I had to pin him down with the waterer now he's a little better. I still have to keep an eye on him. and talk loadly at him when he gets "cocky"
Red's not an unusual trigger -- it's the color of blood and blood is tasty >
But wow -- chickens with color preferences XD So far mine show no preference to color, but they matured in coat season so they've mostly been exposed to blue jeans and a dark green coat. Who knows how they'll behave this summer.