"What's up home chickens?" is a phrase that Zack uses from time to time as an intro to his videos. This phrase was also used as an intro by Rozz in his YouTube videos. Zack also uses "Whats up my babies" as an intro for his videos.
The actual Home Chickens of Scottland were shown in Episode 345 as a prank. Quite a few chickens went into the fireplace (burning themselves to death in the process), or escaped the building.
A LOL replay is titled Home Chickens, showing when Zack first sees the chickens from the great chicken invasion of 2011.
This probably came about, by Zacks fondness of chickens, as mentioned in Episode 404.