Kevin Maurer dressed the dummy as Griswold, the character in the classic holiday movie, and then hung him from the roof above a toppled ladder, the Star-Ledger reported.
For weeks, neighbors applauded Maurer for his originality.
But one night, Maurer forgot to turn off the spotlight on the hanging mannequin before he went to bed.
All of the other Christmas lights were timed to turn off at 11 p.m., so when a passerby saw the dark house with a figure suspended from the garage, he thought the dummy was a real person.
Police arrived at Maurer's house at 1 a.m.
"I'm fast asleep and all of the sudden there are five cops at my door," Maurer said. "I couldn't believe it. I was trying to make him a Monmouth County legend but I got in trouble for it."
Police asked Maurer to remove the dummy from his roof, the Star-Ledger said.
Maurer is now asking for ideas for an alternate role for the dummy.