I have no kids or husband to surprise, yet. But I do have a younger sister (relatively speaking. I'm 23, she's 20). Just this last December we decided to do a birthday trip for my sister. She was in on it, and very excited. She had the option of either having the family do MVMCP, or bringing one friend with her. She took forever to decide, and finally went with bringing a friend.
So the trip finally arrives, and she and her friend head up early. I'm supposed to follow later at night with my parents, driving with them. Instead I took off of work early, raced up there, and met them just in time to check in. They were surprised I was there so early, but I brushed it off and made up some work related excuse. So the three of us got on the monorail to tour the Big Three, as we call the hotels along the MK loop.
My sister's idea was to look at the hotels and then go to Planet Hollywood at DTD for dinner. My idea was different. I had secretly bought 3 passes for MVMCP. Once on the monorail I made a show of pretending that my AP was lost. I got off at MK, claiming I needed to get a new pass. They went on to the GF. I picked up the tickets, jumped back on the monorail and met them at the hotel. Turns out they were starving and wanted to go to eat now. They were just heading out the door, when I told them we couldn't go to DTD. They both turned and asked why, and I flashed the tickets. I think I said something like, "Because we have to go to the Magic Kingdom!" or some such thing. They were shocked. My sister was in complete denial until we actually entered the park. It was such a blast.