Was flying to SYD many years ago with my wife. I had 2A she had 2K. during the night and after quite a bit to drink, I visited the facilities and returned to my seat via her side of the aircraft. As I pulled back the curtain I noted that her light was on. We had not been long married so having approached from the galley on the 747 I bent around the seat to kiss her ......only to find it was 3K and some else entirely!!
Not sure who got the bigger shock...but the female passenger was not amused.
My wife slept on a few feet in front as I retreated from a very awkward F close encounter.