So, you always were honest one to the other, so you explain to her the device, where you find it, how did you fix it. You explain to how it works and what he does.
In first time she doesn't belive you, she things thats just a weird toy or something like that. So, you give her an example.
Both of you spotted a drunk man trying to flirt with a young girl. So, you activate the device and merge them.
She stays little bit drunk, but she is now sexier than before.
The reality change to, you and only Olivia remember the existence of the drunk man and the lady. Their friends completely ignore what happen.
You best friend look at you and say.
"Ok, I was thinking you were completely sick, but that's totally insane. We can do so many things! Can I try ? Pleaase ???"