Peter will like this

Walter takes his device and leaves the room so he has some privacy to surprise his son he searches images he scanned in secret that no body but him knows about and finds his sons girlfriend Alice and activates the I BOD and turns himself into Alice he then puts the I bod on the charger in his lab so nothing happens to it. She then goes to Peters room and sends his son a text to come to his room. When peter gets there he sees Alice leaning on his bed even though she is out of town.

As Peter sees her he says "Alice, when did you get back?". She smiles and says "Son, it's me! I thought since she is out of town you would like to spend some time with her doing things you like to do like going to the science Expo and see what they have!" in Walters voice he then concentrates and says or if I need to I can sound like this in Alice's sexy voice if for some reason I need to pass as her but for now I will keep my own voice as he switches his voice back to his.

Peter says "Oh Dad... Well, that sounds fun! But while you are looking like Alice I obviously can't call you dad! So I will call you by her name and treat you like her while we are out so no one gets suspicious of anything different. That includes kissing and holding hands!".

Walter-Alice replies "Okay, but under no circumstance can your mother find out about this. I left a note saying I got called away in case she gets home before we do!".
Peter then takes her hand and guides her to the car and they head to the science Expo.