Debbie Downer is a name of a fictional Saturday Night Live character which debuted in 2004, and who was portrayed by Rachel Dratch.
The character's name is a slang phrase which refers to someone who frequently adds bad news and negative feelings to a gathering, thus bringing down the mood of everyone around them. Dratch's character would usually appear at social gatherings and interrupt the conversation to voice negative opinions and pronouncements. She is especially concerned about the rate of Feline AIDS, a subject that she would bring up on more than one occasion.
Read more about Debbie Downer: First Appearance in 2003–2004 Season, 2004–2005 Season, 2005–2006 Season, 2010 Appearance, Theme Song, SNL Episodes Featuring Debbie Downer