There are three different types of irony: dramatic, situational, and verbal.
Dramatic Irony is when the audience knows something that the characters on stage or in the text do not know. The tension that the reader or watchers feels until the characters discover what’s “really going on” is born of dramatic irony.
In the beginning of Lego Movie, Lucy tells Emmet that it is “brillant” of him to act like a useless nobody and that he “can drop the act” with her. Lucy doesn’t know that Emmet isn’t acting, but the audience does. This is dramatic irony, and the audience laughs at the chase scene that ensues as Lucy applauds Emmet for being amazing and smart as he eludes the cops during the chase because the audience knows that everything is an accident on Emmet’s part and he really has no idea what is going on. This tension born of dramatic irony is broken when Lucy directs Emmet to fly through the tunnel at the edge of Bricksberg, and he declares that he can’t because it is “against the instructions.” Lucy then asks Emmet about his favorite song, restaurant, and sports team, and when she realizes that Emmet is a brainwashed civilian like all the rest, she yells, “Ohhhhhh, nooooooo!” Lucy is not finally in on the joke that the audience has been in on for a while.
Another example of dramatic irony in Lego Movie happens when Finn’s dad comes down the stairs and starts yelling at Finn for playing with all of his Lego stuff. He tells Finn that they are going to put everything back where it belongs…permanently. As Finn’s dad reaches for the Krazy Glue so that he can glue down all the Legos and prevent Finn from playing with them in the future, the audience realizes that Finn’s dad is the model Finn used to create the enemy Lord Business. The audience knows this and suddenly feels very sad as they realize the implications of the this information: Finn wants to play with his father, and his father rejects Finn, and moreover, mocks his attempts to be creative because of his selfish need for perfection. This tension born of dramatic irony begins to break when Finn’s dad asks what the “kragle” is, and Finn points to its location. The dad opens Lord’s Business’ tower and sees the bad guy, Lord Business. One can see the father’s mouth grimace as he realizes how much the enemy looks like him and sees that the great weapon is really Krazy Glue. When the audience realizes that the father accepts this indirect critique of his actions and has decided to reform his behavior by playing along with his son and asking what Emmet would say to Lord Business, the audience knows that the father realizes that his son has based the enemy on him, and he plans to change his ways to be more inclusive of his son. The tension is broken.
Situational Irony is when a person expects one thing, but the opposite happens.
Verbal irony is when a person says one thing, but means the opposite. Sarcasm is a subset of verbal irony–when verbal irony seeks to be mean.