Thing 1 and Thing 2 Birthday Theme

Decorations
The Thing 1 and Thing 2 birthday party theme colors should be light blue, white and red. 
Set out red tablecloths and place large white circles that are cut out of fabric or felt around the tops of the tables.  (You can also reverse this and use white tablecloths and red circles.)  Use white, red or light blue solid plates. 
Use red, light blue and white balloons and streamers to decorate the party.
On the party tables and around the room place small glass containers (like small fish bowls) filled with red, white or light blue stones or marbles.  In each container place fresh carnations in white and red.  Around the top of the glass container hot glue some of the light blue feathery garland. 

Activities
For a fun activity let the guests make a craft.  Make a fun bank by covering small containers that have a lid with red felt or scrapbooking paper.  Glue on light blue feathery garland around the top of the lid.  Have an adult cut a hole in the top of the lid where money can be inserted.

Picture frames are always fun to make at birthday parties.  Let guests paint wooden picture frames with red paint and then decorate with sparkly gems in white, red and light blue.

Games
For these fun games have party guests split up into two teams.  For each team make up large white circle stickers that say either "Thing 1" or "Thing 2" and have the teams wear them to show which team they are on. 
Fishbowl Frenzy Game
This is a fun relay type game.  The object is to see which team can fill up their fishbowl the quickest. 
Before the party buy two fishbowls (or buckets) and write on them "Fishbowl 1" and Fishbowl 2".  In the backyard or park set up the fishbowls on a sturdy surface about 30 yards from where the teams will line up to begin the game.  At the starting line fill up a large tub with water.  Take 2 plastic drinking cups and poke several holes in each one.  Make sure that when they are filled with water the two cups leak at the same rate. 
During the party - line the two teams up at the starting line and tell them they will have to one at a time dip their cup into the water and then run to the fishbowl and empty it into the fishbowl.  Tell them they are not allowed to plug up the holes on the bottom of the cup.  The first team to fill their bowl to overflowing wins!

Mystery Fishing Game
For the "water" use a large appliance box, hang a sheet across a doorway, or cover a table so that the "fish" (and the person in the water) are hidden from view. Tie a string to a stick and attach a clothespin on the end of the string.  Birthday party guests take turns "casting" the line into the "water". The person in the "water" puts small gifts, favors or candy on the clothespin and then tugs the string to signal that there is a "fish" on the line. 
Then kids pull up the line and retrieve their prize.  This is a simple but fantastic birthday party game that kids adore!  Have lots of prizes because they will all want to do this birthday party game again and again. 

Thing 1 and Thing 2 Scavenger Hunt
Scavenger hunts can be played many different ways and are always fun games to play at a party.  The main idea of the scavenger hunt games is to divide into teams / teams race to find (or do) the items on a list.  Give each team a large red shopping bag to collect their items.
Here are 7 fun varieties of scavenger hunt games.  Free scavenger hunt lists
Divide party guests into "Team 1 and Team 2".

Pin the Hair on the Thing
Played just like Pin the Tail on the Donkey only the kids will try and pin the blue hair on the "Thing".
Place a poster or a large drawing of one of the "Things" on the wall.  Give each guest a piece of light blue "hair" made out of construction paper or poster board.  Place a piece of tape on the back of each guests "hair" and write their name on it. Blindfold children, spin them around, and point them toward the poster. The child who pins their "hair"  closest to the top of the "Thing's" head is the winner!

Tag Gone Wild Games 
Kids love to play tag games (one person is “it” and if they touch or tag another person then that person becomes “it”) and there are many game variations that adapt to many different birthday party themes.   For a fun variation have two people be "it".  Have them call themselves ... Thing 1 and Thing 2!