"Now you've got me thinking maybe I ought to have t-shirts made. With code names on the back." The idea took root and started to make the Doctor more excited than he should've been. "Oooo! What code name would you have? This could be fun!"
He listened to River, then said, "I'm a pretty smart cookie... my younger self will probably put the pieces together without you telling him." A pause, then a shrug. "Or maybe not? How'd you get so buddy buddy with the TARDIS, anyway? "
The Doctor thought about the question, then jumped out of his chair. "Did you know I installed a soft serve ice cream machine? I put it in the hallway, right next to the macroon dispenser! One day I thought, Hey! That's what I need! Soft serve ice cream with my macroons!"