In the early 2000s, Saturday Night Live ran a sketch starring Rachel Dratch as “Debbie Downer”. Each sketch basically had the same arrangement: a collection of people were gathered together for a fun, special occasion, such as going to Disney World, a Thanksgiving dinner, a wedding reception, etc. While everyone else is working to have a good time, Debbie still manages to take every positive thing going on and find the negative in it. It wears very thin, very quickly with everyone else. By the end of the sketch, they all get up and leave her by herself. Even though the skits are funny, they do highlight that naturally energy draining and repelling effect of a negative person on a group. If you have never seen a Debbie Downer sketch, you can check these out to see what I am talking about—and to make sure you do not act like this.
They are hilarious, but illustrate a real social problem: