Foop's first sentence is "Hello Clarice, I mean mother." This is a reference to The Silence of the Lambs where Hannibal Lecter greets the main character, FBI Agent Clarice, this way. His father, Anti-Cosmo, frequently says "Hello, Clarice" as well. This is also a reference to the episode, "The Gland Plan".
Foop calls Cosmo, "Uncle", and Wanda, "Auntie", for some reason despite that they are actually the counterparts of his parents rather than siblings.
The alternate dimension that Foop winds up trapped in is a parody of the phantom zone from Superman II.
Foop's alternate title as "Anti-Poof" is probably a reference to the fact that Anti-Fairies are named after their corresponding fairy, but with "Anti-" placed before their name (Anti-Cosmo, Anti-Wanda, Anti-Jorgen, etc.). Foop seems to be the only exception so far, as his name is his corresponding fairy's name spelled backwards.
Foop seems to have interest in acquiring knowledge, since he apparently is the only Anti-Fairy to go to Spellementary School. Although this is simply likely due to him being the only baby Anti-Fairy.
Foop's apparent favorite word is death.
Ironically, in Anti-Poof, it is revealed Foop hates his own name.
He, like his counterpart, Poof, has no middle name.
He is the only Anti-Fairy that has not experienced a Friday the 13th on the show yet.
In "Timmy's Secret Wish", Foop doesn't even consider the possibility that if he manages to undo the existence of Poof, he would be undone until Jorgen Von Strangle points this out. This may indicate that he is not as intelligent as his father, Anti-Cosmo.
In Spellementary School, Foop tries to be the most popular student at the school and fails to do so. This is a big switch, considering in his debut appearance, he states clearly that as Poof's opposite, he is to be feared and despised throughout the universe.
Even though he is the son of Anti-Cosmo and Anti-Wanda, he appeared alongside them only once.
In The "Terrible Twosome", Foop has the Terrific Twos in the second half of the episode, while Poof has the Terrible Twos.
In "Scary GodCouple", Foop was made Vicky's Anti-Odd Parent, despite that in Balance of Flour, it was mentioned that no Anti-Fairy can be the Anti-Fairies of a child.
Foop experienced a Fairy-clipse in "When L.O.S.E.R.S. Attack".
As mentioned by Foop in Timmy's Secret Wish, his tears are made out of acid.
Foop was supposed to be the antagonist of Poof, until "Timmy's Secret Wish" and "When L.O.S.E.R.S. Attack", where he turns into the antagonist of Timmy.
However, it's stated in both of those episodes that he wants to go after Timmy because he gets in the way of him going after Poof.
It appears that by the end of "School of Crock", Foop might have abandoned his antagonism towards Poof as he is shown being thankful to Poof for saving his life and apologizes for trying to annihilate him all the time. This also may be the reason why Foop attends to Cosmo and Wanda's work anniversary in a following episode "The Past and the Furious" and his new focus on antagonizing Timmy Turner.
He is similar to Stewie from Familly Guy in how they act and speak and in their initial hatred towards their mothers. Like Stewie, he eventualy got over it.
He is the one responsible for the naming of "L.O.S.E.R.S." after his colleagues failed to present a proper name. However, he did not train the L.O.S.E.R.S. members.
He's one of the few anti-fairies who's voice isn't provided by the same actor who plays the main fairies counterparts.
He was supposed to visit his parents for spring break but for some reason they moved and didn't give him the new address.
Despite Foop being connected to Poof, he appeared in seven episodes where his counterpart did not appear.