Most of us have one — a best friend who we're allowed to jokingly treat like crap and expect jokingly crap treatment in return. If you have one of these sarcastic best friends, you know that you don't constantly harass and insult them because you dislike them; on the contrary, you do it because you love them and because you've finally found someone you can have a relentlessly hilarious back and forth with to warm your frigid heart, their frigid heart, and make sure less fragile hearts don't get hurt in the wake of your cold, deadpan humor.
Some famous sarcastic TV friendships include Dr. House and Dr. Cuddy from House, Damon and literally everyone he ever speaks to on Vampire Diaries, and Brian and Stewie from Family Guy (one of my favorite sarcastic friendships). In all of these cases, no one really means any sort of malicious harm towards others, but just has a way of expression that might come off to those outside of the "sarcastic best-friendship" as abrasive or rude.
This Buzzfeed video really hits the nail on the head with what sarcastic friendships look (and sound) like and if you have ever been in one, you'll definitely recognize the exchange.