Pi has daily visits from some local magpies, and one sings like R2D2! She also makes the sound of a car alarm, and a barking dog, which was what I was trying to record that day. When I played it back I realised it sounded like R2D2! It's so weird.
At about 2:00 mins and 3:02 mins she does it (I don't know how to edit movies sorry).
I don't know if someone in my area plays a lot of star wars games or something, but she learnt it from somewhere.