Wake her up the morning of and do a scavenger hunt. That would be fun. Or just go to the airport if your flying (maybe tell her your going to the store or something). My mom kind of did that once, but it was much easier. She works at the airport and told us she needed to stop at her office. We "ran into" my dad who had all the suitcases and they told us not even 2 hours before our plane left.