It simply amuse her, and she loves it. Diana is bigger and taller than you and—of course, thanks to her powers—stronger. Which makes it pretty easy for her to pick you up from times to times as if you were a doll.

It doesn't matter where you two are, if there are people or not. If she wants to pick you up, she'll do it without telling you about it to catch you off guard, she always enjoys your reactions.

Like now, you're both in the Watchtower, you were working on something at a computer before she came up behind you and suddenly swept you off your feet, picking you up in bridal style. "Hey there, love." Diana said softly, looking down at you with loving blue eyes.