Or actually, what not to do. Yellow ribbons on leads aren't decorations, nor does it mean the dog is waiting for an owner in the military to come home. The ribbons signify that the canine isn't receptive to petting or friendly butt-sniffing with another animal.
The visual heads-up was designed by The Yellow Dog Project, a nonprofit organization working on behalf of dogs that need extra space. These include dogs that are seniors, are infirm, or that have not been socialized. They may be working in a service capacity, be recovering from surgery, or they may have fear issues.