How did Darth Vader know what Luke Skywalker was getting for Christmas? He felt his presents.

Luke Skywalker and Darth Vader were having a lightsaber battle... ...and Luke is getting demolished. He knows that unless he does something drastic, he's going to lose. So, thinking quickly, he says to his opponent, ""Darth Vader, I know what you're getting for Christmas."" Darth Vader hesitates for a moment and says, ""How do you know?"" Luke responds, ""I felt your presents.""

Darth Vader and Luke Skywalker... ... are locked in mortal combat. Darth Vader pulls Luke close and says, ""I know what you're getting for Christmas"". Luke responds, ""How?! That's impossible!!!"" Darth Vader replies, ""I felt your presence""

In the vein of today's Star Wars announcement, a topical joke In a deleted scene from Return of the Jedi, Luke Skywalker and Darth Vader are fighting a duel to the death when suddenly Darth says to Luke: ""Not only am I your Father, but I also know what you're getting for Christmas!"" Taken aback by the change of subject and suspecting a trap, Luke replies cautiously: ""How could you possibly know what I'm getting for Christmas?"" Darth Vader: ""Because I've felt your presents...""