No, he had no idea what naughty things she was referring to... though he filed that away for later discussion. "Good memories worth keeping, huh? Well, besides this... there was that time I made dinner for you in Hydroponics... and there was that time we talked forever out on the Obs deck..." He arched his eyebrows slyly, then affected surprise. "Oh, but I guess you're IN those memories already, so it might be awkward for you to visit them!"

He so wants her to blush.

More seriously, he continued, "Hard-won victories, and those quiet moments stolen in the midst of everything. Those are what I like most."

Actually, that WAS an oddly-serious answer from him.