My fondest Christmas memory from my childhood was as a teen dragging a Charlie Brown Tree over to my friend's apartment and decorating it entirely with things from the kitchen and the recycling (well there wasn't recycling back then...but we recycled!) There were origami birds all over it, tin lids punched with a nail and a hammer, popcorn strings, and lots of paper chains. We didn't even have a pail to put the poor thing in, it was sitting on it's little scrap X and we wrapped that in a pretty scarf (we hippies wore a lot of shawl sized indian cotton scarves in the 80's) There weren't any lights on the tree, but we had candles on the steamer trunk we used as a coffee table, bits of metal and cellophane on the tree caught the light and twinkled.
We made mulled cider from a can of apple juice and some ground cinnamon and cloves.
There was marmite on toast and left over popcorn as a meal.
It was fabulous. It captured everything good about the season of Yuletide. It was all about community, and beating back that infernal darkness we northerners suffer through. We could see the light beyond the solstice and the cold didn't matter because we had each other for company.
That's what a tree trimming party is all about to me.