Holy crap!

A heated portable toilet in an Upper East Side park erupted in flames, causing a chain-reaction blaze that gutted three of the toilets and knocked two others out of commission.

The fire erupted in a Port-O-San toilet in John Jay Park on 76th Street near Cherokee Place — where the bathrooms are being renovated — at 11 a.m. Thursday. It was apparently sparked by a faulty electrical connection.

It took firefighters about 15 minutes to extinguish the blaze. No one was injured.