What is the literary term when something serious is happening and there is humor?

Answer 1

http://www.buzzle.com/articles/glossary-of-literary-terms.html#H

Scroll down and read the entry for Humor. See if there's the term you're looking for.

Answer 2

http://www.buzzle.com/articles/glossary-of-literary-terms.html#I

Or maybe Irony.