President Obama's known for his pretty good sense of humor(for example, when the presidential seal fell off during a speech a few months ago, and he said"That's all right, you all know who I am".), and he let out a lot of it when he phoned the ISS on the beginning of March.
Mentioning R2, he said, "Are you guys making him do chores or do dishes up there?" and then the Discovery commander mentioned that they didn't get him out of the box yet, and then joked that he could hear noises from the container and he thinks the robot's trying to say "lemme out".
You should watch the video from the 3:30 mark.