The traditional ugly Christmas sweater...
Hot glue a Christmas stocking to the front of your sweater and use it has a drink cozie for the night. Insert straw to be completely hands free.
For the beer lovers, create a Christmas tree out of beer caps on your sweater.
Using felt create gingerbread men and hot glue those along with letters that read "Oh Snap!" and conveniently make sure the heads are not attached to the gingerbread bodies for the full effect.
Here's a "couple" ideas...
With your significant other or a friend, one of you can be the tree and the other the gift. Using a green sweater for the tree use safety pins to attach garland all around with small Christmas ornaments. For the gift create a bow using ribbon on the front of a plain sweater.
If you want to be really festive, and aren't ashamed of your Christmas game, one of you can wear a sweater and use a hot glue gun to attach felt letters that read "Jingle My Bells" and then, strategically, place a pair of bells underneath that. The other can wear a sweater and hot glue felt letters towards the bottom that say "Feel the Joy" and then above that again, strategically, hot glue a pair of gloves.
If you really "love" your friends...
On a sweater hot glue the words ho-ho-ho like below, with arrows pointing to your favorite people.
[photo] <-- Ho
Ho --> [photo]
[photo] <-- Ho
Sweaters aren't your thing? That's ok...
Get a bag of cheap Christmas bows and hot glue them to a skirt or shorts.
Put a bottle on your head and gather your hair around it, using a hair-tie to secure at the top. Decorate with garland and Christmas ornaments using bobby-pins. Place a small star at the top.
Use a tree skirt to create a shawl and decorate obnoxiously with Christmas decorations. Pair with a jingle bell bracelet.