Your lecture has no effect. She insists that she's Jessica.

"But I'm the real Jessica!" insists Jessica.

"Sure, just as much as I'm the real Trish," you tell her, trying and utterly failing to sound like David using Trish's voice. "That is, a flawless fake created by turning a living, breathing human being into the ultimate girl suit. Without even asking permission. Who's inside you? Jimmy, maybe? Just the sort of thing he'd do."

"I was just joking!" she says, sounding exactly like a sincere Jessica. "Yeah, I put on Trish and zapped myself with the brown 'pen' thing and all that, but I took her off before David came. I'm the original Jessica!"

She's been so distracted that you have no trouble picking up the black 'pen' she's imprudently left in plain sight and within easy reach. You say in perfect Trish tones, "There's an easy way to find out," and point the business end at her.

"No, don't--" is all she can say before her naked Jessica body goes hollow and crumples to her bedroom floor.