The American unofficial code name for the Ohka suicide weapon deployed by the Japanese near the end of WWII.
The Ohka (trans.: cherry blossom) was a slender fuselage with skimpy (and inadequate) control surfaces and a cockpit in the middle, with all the space forward of the cockpit stuffed with explosives and the space aft of the cockpit containing rocket engines. Dropped from a bomber, the rockets would ignite, and the pilot had barely enough control available to him to roughly guide the "aircraft" into a collision with an Allied ship. Theoretically, it was a bit more cost effective than expending a whole airplane for a kamikaze attack, and its speed and size would make it more difficult to shoot down, but in practice, it was just too difficult for the pilots (especially given the quality of their training at that stage of the war) to score hits. It was also relatively easy for Allied fighters to just shoot down the parent bombers first.
Upon learning of the Japanese name for these things, someone in the Pentagon who actually spoke some Japanese pinned the name "baka" on them, and it stuck.