He's Incredibly Stupid

Swept overboard in the Gulf of Tonkin in 1967, U.S. Navy sailor Doug Hegdahl was captured and sent to the infamous Hoa Lo Prison. Feigning illiteracy and ignorance, he earned the nickname "The Incredibly Stupid One", granting him the freedom to sabotage enemy trucks and memorize the names and details of 256 POWs using the tune of "Old MacDonald Had a Farm".