The man claims he was held down twice over 48 hours and tattooed repeatedly by people he knows, CBS Philly reports.
Detectives say the victim first called "911" at mid-morning Monday telling police about the attack at the home, where he lives in a basement apartment with three men and a woman.
"It appears that these are all individuals that he knows, associates of the complainant, so this is not like this is a random incident," Lt. John Stanford of the Philadelphia police said.
The four people were being interviewed by detectives.
Police say the tattoos, nearly a dozen in all, fully covered the lower part of the man's arm, and included obscene images and racial slurs, according to investigators.