A long long time ago when I was a wee lad, I was with the family on the way back from holiday on a flight operated by Britannia flying into MAN. The Captain had been a bit of a banter merchant on the PA as soon as we had boarded... Joking about this and that... The pre-flight announcement had most of the passengers in stitches.
About 30 minutes into the journey, the skipper came back on the PA and said
"Ladies and Gents; I'd like to announce that unfortunately we cannot accomodate any visitors to the flightdeck during our flight, however, we do have a spare seat up here which one lucky child can sit in during the landing back at Manchester. If you would like to sit in the spare seat, all you need to do is draw a picture of my colleague, First Officer XXX, the child who draws the most realistic picture, will get to sit in the flightdeck"
Now, this was a dream for me as a 6 year old plane fan, so I began drawing what I thought the FO would look like - we hadn't seen him all flight so it was obviously a guessing game... To cut the story short, I didn't win, but I thought it was a great idea and I'll never forget that flight. It's such a shame (as the above poster has also stated) that I won't be able to do such a thing for a passenger one day.