She went excre-mental.

According to a report, a female passenger on a Southwest Airlines flight to Chicago allegedly removed all her clothes and defecated on her seat as the aircraft was landing.

Authorities were summoned to Chicago’s Midway Airport on Saturday after Flight 418 from Philadelphia touched down, and one passenger surprised everyone in the cabin by undressing and relieving herself on a seat, as per NBC.

Southwest responded to the incident by stating, “Our teams are contacting those who were on board to express regret for the incident and any inconvenience caused to their travel plans.”

“Nothing is more important to Southwest than the safety of our customers and employees, and we appreciate the professionalism of our flight crew,” the statement concluded.

It wasn’t clear what happened to the passenger.

The plane was taken out of service for cleaning, according to the report.

Last month, Southwest had a more serious mishap at Chicago Midway Airport, when a landing jet had a near-miss with a taxiing jet due possibly to a sun glare, according to the National Transportation Safety Board.

Southwest did not respond to The Post’s request for comment.