Mega tree - is a term used to describe a tree made of Christmas lights.
There are many varieties of mega trees including tall ones, short ones, skinny, wide, single color, multicolor, static, animated, etc. Look around at the Christmas displays on PlanetChristmas and you'll see what I mean.
I added a mega to my display in 2007. It was only a 12 foot mega tree with green colored lights. Here's a picture of it during the day.
I didn't want to dig a hole in my yard so I created a base for my mega tree out of a bucket of concrete. I didn't plan on using guy wires and decided I was going to try create a way to add supports at the base. I cut out four holes in the bottom of the bucket and inserted some pieces of pvc.
As you can see one piece went all the way through while the other had to be divided in two. I sealed all the seams as best I could with silicone to keep the concrete in. I inserted a center piece of pvc for a sleeve to slide the main pole of the tree into. Then I pored in slightly less than 40 pound bag of concrete and let it dry.
In the end, I couldn't really use the self supporting pipes because the ground is not level where I put the tree so I decided to use 3 guy wires. I highly recomend using guys wires and have never had a problem with it falling over. I use wire that is designed to attach to a stake in the ground and a dog collar on the other end.