Betty Lou is a woman, probably Japanese, who makes a one-time appearance in the Season 2 episode of M*A*S*H titled "The Incubator". The part of Betty Lou was played by Helen Funai.
About Betty Lou[]
Hawkeye and Trapper travel to Pusan to the 728th Evacuation Hospital in order to borrow one of their incubators. Meeting resistance from the supply officer, Major Arnold Morris, they go up the chain of command to see the Commander, Colonel Lambert. Unfortunately, Colonel Lambert is more interested in the good life. They find him in his sumptuously furnished house, enjoying fine food and wine and being served by his female companion whom he calls "Betty Lou". Among other things, he tells Betty Lou to prepare a bath for him with lavender in it for the afternoon.
Betty Lou's nationality is never mentioned but she is seen in traditional Japanese clothes, so it is possible that she is a Japanese woman whom Lambert brought over to Pusan. It is also possible that Betty Lou is not her real name, but a nickname given to her because he cannot pronounce her real name.
Betty Lou with Lambert. Note the ring on the 4th finger of her right hand.