Bluto watching the sorority girls (Dramatic Irony)
The sexual thrill that Bluto gets from climbing a ladder and watching the sorority girls in various states of undress is based on the fact that he is spying on them non-consensually, which creates a dramatic irony. The girls do not know they are being watched, and un-self-consciously have a semi-nude pillow fight, as Bluto watches, delighted. The discrepancy between what the sorority girls know and what the viewer knows—that Bluto is watching them non-consensually—creates an instance of dramatic irony.
Wormer's revenge (Dramatic Irony)
Throughout the film, Dean Wormer is plotting against Delta to try and get the fraternity kicked off campus. He is fed up with their pranks and antics, and wants to get rid of them once and for all. For much of the movie, the viewer watches as he plans to take them down; meanwhile, the Delta brothers themselves they have no idea and continue innocently going about their business on campus, which accounts for some dramatic irony.
Neidermeyer cares more about his horse (Situational Irony)
While Flounder is working in the stables, Neidermeyer gets angry at him for hitting his horse and not being more humane to the animal. The comedic irony is that, in scolding Flounder for being careless, Neidermeyer hits him, showing that while he believes that horses are deserving of humane treatment, he evidently does not extend the same concern towards actual humans.
Horse's death (Dramatic & Situational Irony)
Bluto and D-Day prank Flounder by telling him he must kill Neidermeyer's horse, while sending him in with a gun with blanks in it that will not actually kill the horse. Flounder's ignorance about the fact that the gun has blanks makes another instance of dramatic irony, in which we know something he does not. The scene gets even more ironic when Flounder shoots the gun at the ceiling and the horse falls dead from shock. Bluto and D-Day did not expect for the horse to actually die, adding situational irony when the horse drops dead simply at the sound of a loud noise.
