Well at least a chicken isn't going to drag anyone down the street and stop at every fire hydrant and bush. Think of all the attention you'd get and all the opportunities to spread the word - "chickens in every backard."
My chickens do know certain verbal cues - "do you want some food" (treats)- they come running! "Time to go inside"- either tractor or coop, they walk ahead of me on their own. One day I called to my dog to "get inside" and all 3 hens went and got into the coop. I almost died laughing!!!
I was actually just thinking of trying that with a harness on my giant Australorp roosters! I tried it once a few years ago.....don't think it worked that well that time though!
The string and the corn story reminded me of something. It's a bit off topic but when my husband was small he would tie a string to the leg of a Japanese Beetle and lead them around like a little flying kite. The strange things kids will do.....