A downer, unfavorable situation, a nuisance: Something that would harsh one's mellow.
That Theresa is a real bummercloud, man. Ever since I got her pregnant she has has been raining the bummer
by Dr_tesseract February 25, 2010
1 more definition
-Verb- as in to bummercloud, to hurt someone deeply and joke about.
I sure did bummercloud that Melissa girl, hah!
by HRH114 March 02, 2010