An expression used to show digust at the Christmas season, made famous by the fictional character Ebinizer Scrooge in the Charles Dickens novel 'A Christmas Carol'
Guy: I love Christmas, Don't you Mr Scrooge?
Scrooge: Bah Humbug
Used to express grumpydislike of something generally regarded as enjoyable, or as a response to someone who dislikes things that are normally liked by all.
Alice responded: I have no time for jokes like this, they are just not funny to me!
BahHumbug is usually used in a sentence that talks about something or someone they don't like, it is used in novels such as A Christmas Carol by Charles Dickens
Person 1 "Mery Christmas Person2 "Whats so merry about it, BahHumbug, I say!"