"The One With Mrs. Bing" is the eleventh episode of the first season of Friends, which aired on January 5, 1995.
Phoebe incites Monica to whistle at a hot hunk they see walking on the street, he turns and doesn't see the ambulance which knocks him into a coma. The two try to make it up to him by taking extreme care of him, even as they fantasize about him as the most charming of guys. The game of 'who cares for the coma guy the most' reaches obsessive levels, with the two girls unable to spend a minute away from him, until the guy convalesces from the coma. The girls explain how they've been taking care of him, but his less-than-grateful attitude turns them to ice and they ditch him.
Chandler's mother, Nora Tyler Bing, is the guest on The Tonight Show with Jay Leno, which Chandler is uncomfortable watching due to his mother's more-than-embarrassing remarks. He does, however, learn that she's dropping by to visit him. Meanwhile, Rachel's Paolo arrives from abroad too, much to Ross' displeasure. At the Mexican restaurant where the guys have dinner with Nora, Rachel turns up late as she takes advantage of Paolo being around, which doesn't help Ross lift his mood, so he turns to tequila shots. He talks of the Italian problem with Nora, who seems understanding enough, but her animal magnetism and the dozen shots in his head bring Ross and Nora close enough for their lips to touch. Unluckily for Ross, Joey witnesses the kiss. Ross tries to explain everything to Joey, who is mad at Ross for "breaking the code (of never kissing a friend's mom)" and also for not thinking that his mom is as hot as Nora. Eventually, Ross tries to lie to Chandler that Paolo kissed his mum, but he can't pull the lie off and ends up confessing everything. Unsurprisingly, Chandler gets mad at Ross and remains mad at him for some time, until he gets the courage to face his mother, after which he makes his peace with Ross' incident. Rachel, a big admirer of Nora's works, tries to imitate her idol by writing her own book, but, as it turns out, she's not very good at mixing human genitalia with euphemisms, and the guys pretty much make fun of her draft work.