“Hey, Artoo, you look a little different today.”
“Yeah… you. Did you get a haircut?”
“Uhhh… no, no, I’m on a diet. I’ve lost a few pounds.”
“Ahh, that explains it. Wait… could you speak English yesterday?”
“Oh, alright then. Carry on.”
If Darth Vader ever wants to send a mole over to infiltrate the geniuses over in the Rebellion, I think he just found his solution. An R2-D2 disguise for a Stormtrooper so good, even the intellectual deities that pulled off the R2-D2 college building prank couldn’t figure it out.