Teeth For Two - The title is a reference to the saying "tea for two" and/or phrase "table for two" which is commonly used in restaurants.
CatDog - This is the episode of same name from the Nicktoon, CatDog.
Star Wars Episode 3: Revenge of the Sith - Mrs. Dinkleberg aging after Mrs. Turner stole the former's car is a reference to Darth Sidious' face aging caused by his attack being deflected by Mace Windu's light saber
All the nicknames Cosmo put for Timmy' teeth are puns:
Roman Catholic Devotions - Dr. Bender's line "It worked for the pilgrims" is a reference to the devotions at St. Charles Borromeo.
If you look carefully at the pictures in the restaurant, there's a picture of Britney Britney with a fairy crown, but in all other episodes, Britney Britney is a human.
When Jorgen starts hugging Cosmo and Wanda you can see them wearing their formal clothes, but in the treehouse they are wearing their normal clothes. When Jorgen finally lets go of Cosmo and Wanda in Timmy Turner's bedroom, they're wearing their formal clothes again.
Timmy is shown to have a lot of teeth, but when Dr Bender yanks out the loose tooth, Timmy has no teeth until the Tooth Fairy gives him new teeth.
Jorgen calling Cosmo and Wanda as his closest friends.
Jorgen pulling off Timmy's teeth.
People calling Jorgen a bully.
Cosmo having a crush on the Tooth Fairy and Wanda getting mad at him.
When Wanda gets mad at Cosmo for showing his attraction to the Tooth Fairy, Cosmo will say stuff like "Look! I'm a donkey! Hee-haw!" and "Look! I'm clamming up!" and then poofing into that animal.
Cosmo mentioning one of Timmy's tooth nicknames to him.
Cosmo and Wanda poofing up notes to Timmy owing the latter.