A bus passenger made a splash early Thursday when she attacked a bus driver with the contents of her cup in the South Shore neighborhood.

The confrontation happened shortly before 1 a.m. in the 7900 block of South Exchange Avenue, according to Chicago police.

The woman exited a CTA bus, walked to the driver’s side window and threw the liquid in her cup onto the driver’s face, police said.

The driver, a 31-year-old man, was treated by paramedics at the scene, according to police, who didn’t say what was in the cup.

No one was in custody early Thursday, police said.