Dramatic Irony: the Rat Man's advice about trust and belief
Early on, as Phase Two of the Trials are about to begin, the Rat Man tells the Gladers that they should "never, ever believe their eyes" or their "minds, for that matter." He says that "This is why we did the demonstration with the hanging bodies and the bricked-up windows. All I will say is that sometimes what you see is not real, and sometimes what you do not see is real" (56). These statements are ironic in that the Rat Man himself should not be believed. How do the Gladers know that they should believe or trust the Rat Man? For all they know, he could be telling them lies, too.
Situational Irony: Teresa's betrayal of Thomas
Ironically and painfully, Teresa betrays Thomas and ruins their friendship forever because she wants to protect him. In order to prevent WICKED from killing him, Teresa follows their instructions. She ultimately tells Thomas that "They said they'd kill you if we didn't do everything just like they told us. No matter how horrible. I'm sorry, Tom!" (303.) She had to hurt him in order to keep him alive–she even pretend to "kill" him in order to ensure he survived.
Situational Irony: Minho's neck tattoo
Minho's neck tattoo label is 'the Leader', a role which he finally accepts and then proceeds to take very seriously. This is ironic because out of all of the Gladers, Minho is probably the most rash and hotheaded. This is not to say that Minho does not have his own style of leadership, but ironically, Brenda's prediction that Thomas is more like the leader type (166) comes true when Thomas discovers the plaques that WICKED put up all around the town.
Dramatic Irony: The choice between Brenda and Jorge
When Thomas and his friends finally get on the Safe Haven Berg, the guard there forces him to choose between keeping either Brenda or Jorge with them (345). This is ironic because it is eventually revealed that Brenda and Jorge are not the 'civilians' that the WICKED personnel calls them, but rather that they are actually workers for WICKED. Ironically, this last challenge by WICKED really is a test: Thomas made the right choice by using force to keep both of his new friends.