What's up with that?

My three year old is emotionally attached to her bathing suit.  She sleeps with it.  As soon as she gets up in the morning, the pajamas come off and the bathing suit goes on.  Wonderful-stay-at-home-dad has convinced her to take it off before they go out to run errands "to keep it safe."  But then, as soon as she gets home, it goes back on.  And, no, we don't have a swimming pool.