A person who continually refuses to admit that they are sick, even though they may be coughing, sneezing, and/or sniffling. Particularly applied to colds and coughs.
Person 1: "You sound really sick."
Person 2: "Oh, I'm not at all *cough cough*"
Person 1: "Maybe you should take some medicine"
Person 2: *sneeze* No, I'm fine, I'm not sick"
Person 1: "You're just a dooma dooma"