(TMZ) Cops showed up to the Lohan residence in New York last week ... after a member of the family claimed they were receiving threatening phone calls ... but it wasn't Dina ... or Lindsay ... or Ali ... or Michael Sr. ... or Jr. -- it was the youngest Lohan of them all, 15-year-old Cody.
Law enforcement sources tell TMZ ... Cody called the Nassau County Police Department on Thursday and told officers a mystery caller was blowing up his cell phone and threatening to "harm him."
We're told cops checked out the Lohan home -- looking for anything suspicious -- but we're told they didn't find anything out of the ordinary.
Cody's mom Dina is still in Los Angeles, having attended the Kardashian wedding -- but sources close to the Lohan gang tell us family members are taking the threats very seriously and Cody is under proper care. more on this story