I'll start because mine is very simple. It still plays out in my head.
In about 1981, when I was just 6, that was when the toyline, the Masters of the Universe was first hitting store shelves. And at that age, I thought it was just the coolest thing ever! I remember those weeks before Christmas, walking thru the department store toy aisles and seeing an entire lane of those MOTU action figures, vehicles and playsets and just BEGGING mom and dad for just one!
But of course, they said what all parents say at that time of year;
"Wait and maybe Santa will bring you some for Christmas." (don't you hate it when parents say that? <_< )
The thing I wanted most of all was Castle Grayskull, because the art on the box just made it so damn appealing!

The commercial for the Castle didn't help either!
Castle Grayskull commercial
For some reason, I had a fascination with trap doors and the fact the Castle had one made it all the more appealing. I begged and begged for the Castle for Chrostmas, even writing a late letter to Santa. I swore in the days before Christmas that I would play with it every day if I got just it.
Well the days passed (SLOWLY) and Christmas Eve arrived. I saw no big boxes under the tree so that wasn't a good sign. My brother spent the night at my Grandma's and I finally went to bed (barely). The morning came and I was not allowed out of my bedroom to see the tree until my dad went and got my brother. Talk about torture!
Anyway, after he left to go get him, my mom told me I could come out for a little peek. I snuck out and looked around the corner, and lo and behold, there was Castle Grayskull right in front of the tree, in that glorious box, unwrapped! (My folks reckoned I'd get that sucker tore open in record time so why bother wrapping it?) I wanted to dive right at it then and there but mom made me go back to my room. Few minutes later, my dad pulled into the drive and I got the call to come on out. I bolted from my room and let out the biggest holler as I went right after that box, and me and my brother dug into the presents!
And I was not without something to play with the Castle, as my aunt had went to the store for my mom and selected my first two MOTU figures for her;

Stratos and

Teela
I also got some great stuff like a stuffed Papa Smurf toy, and I believe that was the year my brother and I got the Atari and a few games to go along with it.
All I can say is that particular Christmas, it was just magical and has been my favorite Christmas morning by far.
