Though only two are actually brother and sister, Ross, Monica, Chandler, Joey, Phoebe and Rachel are all closer than siblings.
Most of their relationships with each other date back to when they were younger, yet even the later additions to the gang have shown time and time again that they would do anything for the others. We've seen plenty of altruistic acts of friendship, such as Monica taking in Rachel after she left her wedding, the whole gang saving dozens of Christmas trees just to put a smile on Phoebe's face, and everyone travelling all the way to Las Vegas to support Joey's career.
However, like any friendships there are ups and there are downs, and after ten whole years of being on TV, there is no shortage of downs. Sometimes there are arguments and disagreements that last just one episode, and sometimes these things can span over entire seasons, but when you really look at it, some of the things these so called 'friends' have done to each other are down right awful.
10. Ross Told His Parents Chandler Smoked Pot
Trying to get the in-laws to like you can be a mammoth of a task in itself, but for Chandler Bing it was made even harder by one of his best friends. Though at the time the friend in question would have had no idea Chandler would end up marrying his sister.
When Jack and Judy Geller come round for Thanksgiving dinner, unaware of Chandler and Monica's dating situation, it quickly becomes clear that Monica's parents aren't a fan of her boyfriend. When Judy suggests that Chandler is stoned again, Ross explains everything to his sister and his friend.
Back in college, when Ross and Chandler shared a dorm room, Mr and Mrs Geller walked in and immediately smelt pot. Ross quickly blamed Chandler for this, and the Gellers' disdain for their future son-in-law was born, lasting for years until Monica revealed the truth at Thanksgiving.
Luckily for Chandler, this ended up as a net positive however, with Jack and Judy discovering a new found respect for him sticking with Ross for all these years and now 'taking on Monica as well'. Despite the happy ending, this is still a dick move on Ross' part.