She tries to

“N-no! It’s not true! It’s all lies!” Becky yelled. “Cat’s lying. She’s lying. I didn’t wet myself. I didn’t!”

“Why, Becky, there’s no need to lie. You still have a diaper rash,” Cat said as she turned Becky around exposing her completely, her crotch still had little red bumps.

This also let Adam see her chest completely for the first time. His eyes widened. “Wow, you really got nothing there.”

Becky’s eyes went wide as saucers as she realized her mistake. “No… I… it’s not true… it’s just… an illusion. This is all… f-fake,” Becky cried as she covered her body.

Becky’s eyes caught a figure in the corner of them and she froze as Marge emerged from around the corner and she was not happy at all.