After finishing cake and ice cream, Obi Wan hands Luke his first birthday gift.
Just before he can open it, Vader shouts "It's a Millenium Falcon action figure!" Obi Wan throws a disapproving look at Vader.
Luke tears off the wrapping paper to find a Millenium Falcon action figure. He looks to Vader and asks "How did you know?"
The sith lord takes two long Vader breaths before replying, "...I felt your presents."