The sicko perp accused of raping 4-year-old twins in Pennsylvania flashed a huge grin and spat at a Post photographer Wednesday following his arrest in New York.

Isaiah Metz, who was wearing pajama bottoms and no shoes, laughed immediately after firing the spitball and screamed “b—-h” as he was hauled by cops into Manhattan Criminal Court.

The 22-year-old — sporting unique bright red hair — had both his hands and feet cuffed after being nabbed hours earlier in Yonkers.

The accused fiend had allegedly attacked two NYPD cops when they tried to take him into custody on the heinous sex assault charges at a Midtown homeless shelter on Tuesday morning, police and sources said.

Metz, who is accused of punching and biting the cops before fleeing, had to be tased when fugitive task force officers eventually caught up with him late Tuesday, the sources said.

He was briefly hospitalized before being brought to the Midtown South Precinct where he was slapped with a slew of charges, including assaulting a police officer, resisting arrest and criminal trespass.

The suspect was initially being sought for allegedly raping the young twin girls after he was adopted into a foster family in Goldsboro, Pennsylvania, police sources said.

He is facing a total of 115 charges, including for child pornography offenses, in the horrific Pennsylvania case.

Metz is already on parole for allegedly attacking another cop in Pennsylvania, CBS reported.