Of course not. She wants you to prove it.

"That sounds like a load of bull," she says. "There's no way something like that could work."
"Well, that's why I got you up here, so I can test it."
"On me."
"Yeah."
"So you could see me cum?"
"Sure."
"Why don't you test it on yourself?" She asks.
"Hang on," you tell her. You're sure there was something on the manual- ah, there it is. You hold it up in front of you to read it. "'Warning: do not use device on persons who are also holding or are in direct contact with the device. Dangerous feedback loop may occur.' I've no idea what that means and I'm not keen to find out."
"Bloody hell," Ana says. "Alright, fine, hit me. Then we can both know it's bullshit and I can go back to my homework."