When Maidenform converted factories to assist the U.S. military during World War II, the bra brand manufactured two things: parachutes and pigeon bras. Or, as they are known in polite society, pigeon vests, made out of bralike materials and designed for paratroopers to strap to their chests. (Seen above, or on a paratrooper here.) After landing in a war zone, the paratrooper would undo his pigeon's bra, load the bird with a message, and send it back to home base.
The Smithsonian's National Museum of American History blog recently unearthed documents and photographs from Maidenform's manufacture of 28,500 pigeon vests:
The vest was shaped to the body of the pigeon, leaving their head, neck, wing tips, tail, and feet exposed. The vest would be attached to the outside of the paratrooper's jacket ... The pigeon carried messages in a tiny capsule attached to their leg. The capsules could contain messages, blood samples, or even tiny cameras. Oftentimes, these carrier pigeons, also called homing pigeons, were the only form of communication during World War II. They were also the most secure and reliable. Homing pigeons were the least likely form of communication to be intercepted. More than 95% of the messages they carried were successfully delivered. Due to their obvious necessity for wartime communication, approximately 56,000 carrier pigeons were trained for war missions in World War II. This was the height of carrier pigeon use.
We can only assume that Maidenform vests were, accordingly, the height of carrier-pigeon style.