They went to a thrift store to find the flawless 1980's winter-in-Chicago ensemble and put it on a dummy which hung from their gutters with such realism that it freaked out a passerby.
Chris Heerlein's festive display includes an homage to the iconic scene from 1989 Christmas film "National Lampoon's Christmas Vacation" where blundering dad Clark Griswold dangles from his house while putting up decorations.
The family reportedly purchased a dummy online and put a Clark Griswold mask on it, as well as dressed it in Clark-inspired clothing.
KXAN reported that the Heerlein family in Austin bought a dummy and had it appear to be hanging onto their roof.
But one man, identified as a veteran named Alfred, thought someone was really in danger.
A NEST camera at the door of the home captured the whole incident as the man tries to save what he believes to be a person.
"Oh mister, please hold on", the man said before wrestling with the ladder.
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To combat that, the Duchess of Sussex should not be afraid to play a longer game. "Kids are an interrupter; they mess it all up". Obama told some 19,000 audience members on Saturday. "Thankfully I get more (and more regular) sleep these days", she said .
Although "Clark" is clearly a dummy, people walking by were concerned enough to call for help.
"He was doing everything he could to get the ladder!" "He didn't give up".
The family also placed a sign at the bottom of their Clark Griswold display to caution other passerby.
An Austin police officer showed up after the 9-1-1 call and spoke to the nanny who was home at the time.
"We'd love to be able to find him and reach out".