What is ironic about what happens to Tea Cake?

The irony is that Janie is protecting herself against Tea Cake who has rabies. She ends up shooting him like one would a dog who has rabies. When Tea Cake comes back from the outhouse, he has a strange loping gait and a clenched jaw. He believes that Janie is not sleeping with him because she is interested in Turner. He grabs the pistol and aims it at Janie. He fires three shots, all blanks. Janie grabs the rifle, and they both fire at each other at the same time. The rifle is slightly faster, and Tea Cake falls to the ground, biting Janie's forearm.