irreverent
adj.adj. showing a lack of respect for people, ideas, or traditions that others think are important. You use this to describe someone who makes jokes or comments about things that are usually taken very seriously.
adj. showing a lack of respect or seriousness, particularly toward established traditions, authority, or sacred things. Often carries a slightly humorous or rebellious tone.
The comedian made irreverent jokes about the president.
The irreverent tone of the book shocked many critics who expected a more traditional history of the war.
While some found the irreverent portrayal of historical figures to be a refreshing critique of nationalism, others argued it undermined the gravity of the events being described.
From Latin irreverēns. By surface analysis, ir- + reverent.