Broken Aesop: "A Bully for Parker" seems to constantly promote the message that it is wrong to hold grudges, especially when Parker's attempt to get back at a bully at a school reunion goes horribly for her. However, Parker really was not looking for revenge as much as self-defense, since she thought the bully was setting up a prank to humiliate her.
Eagleland Osmosis: The characters randomly discuss the Bible belt, the War on Terror, illegal immigration, and Dee once tried to obtain a pardon from the President, despite being a Canadian show. Of course, it is possible the show is set in the U.S.
Earn Your Happy Ending: The season 2 finale sets up that Simon will end up in a happy marriage with Chicago and a succesful movie producer.
Naughty Nuns / Nuns Are Funny: In "In Dee Club", Victoria neither confirms nor denies she had sexual relations with a nun at a Catholic school she attended. The nun in question is briefly seen in the news, with her eyes covered by a censor bar to remain anonymous.
Negative Continuity: In the pilot, Chicago is Blake's cousin and lives with her parents. In "Giving Up Dee Ghost," she is his niece and his sole living relative (which would mean her parents are no longer alive).
Not So Different: Dee and Victoria are both self-absorbed Jerkasses. Victoria just does a better job at hiding it, which makes her more of a jerkass.
Oblivious to Love: Parker is crushing on her boss Blake Bellamy, who alternates between somewhat returning her feelings without acting on them to being completely unaware of Parker's crush.
Reunion Revenge: In "Bully For Parker", Parker plans an elaborate revenge for her high school reunion, but has second thoughts when she spends some time with her most vicious tormentor.
Reused Character Design: The show's designer is really really keen on reusing character designs - and does so with actually named characters, including the show's antagonist (or #1 talk show host and Nobel Prize recipient really does moonlight as a waitress).
The show seems to adore this trope. One episode features Simon losing weight thanks to a testosterone pill. Another episode feature Hal being made over into a muscular hunk. And arguably, Parker's backstory of being overweight.
Vitriolic Best Friends: Despite their contrasting personalities, Parker and Chicago are on friendly terms with each other more often than not, to the point that Chicago even becomes Parker's personal confidant on occasion.