Only funny if you've used a GPS

My mom came down to visit last night to help me do more decorating-type stuff over the weekend. And they had this special on volcanoes on the Discovery Channel, which I am obviously a sucker for.

Guy on Documentary: We placed a state of the art GPS unit on the volcano to track any changes in the crater.
Me: ..................ROFL
Mom: O_o? What's so funny?
Me: LOLOL! every time the earth rises, it goes, "Recalculating route"
Mom: LOL!