A drunk off-duty Chicago cop dressed as “Pennywise” the clown slugged an on-duty officer in the face after she was denied entry to a nightclub while out partying for Halloween, a report said Wednesday.

Karina Salgado, 30, was arrested for the boozed-up slug-fest outside a Boystown nightclub called Broadway at about 1:20 a.m. Friday, CBS Chicago reported, citing police.

Salgado had initially been turned away at the door, but still tried to force her way inside the western-themed bar that hosts drag shows and is open until 4 a.m., the report said.

Somebody at the club called police to report the costumed cop’s behavior.

Responding cops told Salgado she wasn’t allowed inside, but she again tried to walk in, leading to a confrontation that led to the attack.

Salgado, who’s been on the force for two years, was charged with criminal damage to real property and resisting or obstructing a peace officer, the network reported.

Salgado’s mugshot shows her dressed as the creepy clown from Stephen King’s “It.”

CBS Chicago reported that the officer has been transferred to the Alternate Response Section — a unit that fields non-emergency calls to cops.