Actor, T-Mobile star and Saturday Night Live alum Bill Hader helped a high school student pull off a "senior prank" at a New York high school via Make-A-Wish. 

The students were gathered together and thought that the special guest was a fireman who would show a safety video starring students, when suddenly Hader's voice rang out over the speakers. 

Actually, it was Stefon's. 

"Hello, hello? Can anybody hear me? I just want to say something. Elma's hottest high school is Iroquois. It has everything; a principal who fist bumps, two water fountains ... ," Hader said in the character's voice before stepping into the gym in front of the screaming students. 

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[Via Uproxx]