TyLon Pittman, from Jackson, Mississippi, told his mum he had called 911 after watching clips of the family film on Facebook and becoming scared.
However, his mother TeResa did not believe him until Byram police officer, Lauren Develle, knocked on the door later that evening.
TyLon’s big brother, who was home for Christmas from his role in the Air Force, filmed the visit on his phone and posted it on his Facebook page to share with friends and family.
“I can NOT make this up!!!” TeDera Dwayne Graves wrote.
“My five-year-old brother called the police and said that the Grinch is stealing people’s Christmas and he don’t want him to steal his, so they really came to our house!”
Ms Develle, whose favourite Christmas film just happens to be the Dr Seuss classic, told the worried youngster she would protect gifts from the Grinch and take him to jail if he tried to steal Christmas.
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During a visit to the police station, TyLon – who wants to be a police officer when he grows up – told officers if he saw the Grinch he would say “put your hands behind your back and get down on the ground”.
TyLon said he would then ask the Grinch “Why are you stealing Christmas?”, and hold him until the police turned up to lock him up in a cell.