When I was growing up, my sister and I were always allowed to open one present on Christmas Eve. It was always a pair of pajamas, and we loved having new duds to drift off to sleep in as we waited for Santa to arrive. My husband's family had the same tradition, so when we got married and had kids of our own, we carried that tradition forward.
(Side note: When talking to a friend about it this week, she said that they did the same, and wondered if her parents had done that so to have everyone looking nice in the Christmas morning photos. Genius.)
My husband and I always buy each other a new pair of pajamas as well. His pair that I had given him last year had a rip down the entire inner seam of his right leg, so he needed a pair. As for me, I just like a new pair to drift off to sleep in as I wait for "Santa" to arrive.
How about you? Do you give pajamas on Christmas? Do you open any gifts on Christmas Eve?