1. After lunch with a friend on a Saturday, the friend will sometimes ask what you have planned for the rest of the day. Partly because it sounds lame somehow to reveal your actual plans (get in bed with laptop, search Manhattan for the shampoo you really like that your "place" stopped selling, etc.) and partly because you're not sure if the friend wants to keep hanging out so you want make it clear you're "busy," you offer this vague but firm response, something like, "Ahhh, got a bunch of different things to take care of. Thank god it's nice out!"
2. Whenever someone prefaces a story with some kind of serious, whispered "please don't tell this to anyone" request, the other friend will - basically without fail - respond in this completely overdramatic, theatrical way: rolled eyes, hands in the air... "Of course not! Who would I even tell??" she'll say, as if she just arrived in New York and lives alone in a sewer and knows no people.
3. Anytime a friend shows you a picture for the first time of someone they've just started dating. ("He looks so nice!")
4. When you mention a party you were invited to and your friend realizes she wasn't invited, she'll often say something like "Ohh, I'm so offended... I guess Zach just doesn't think I'm cool enough!" in this exaggerated, "sarcastic" way. "Yeah," you'll say, "I mean, it's not like it's some great honor to be invited to his party or anything, you know?" Your friend will respond, "Yeah, I honestly don't care," as she blithely scrolls on her phone. (Actually, in this situation, both parties are being disingenuous!)
5. Whenever a friend is recounting in unusual detail a ~~crazy~~ night out or a work trip or anything they've done, really, and you rotate through like seven two-syllable remarks ("So fun." "Oh, wow." "Really??" "Crazy.") during the 8-minute narrative. (Hah, I love how this last one basically just boils down to, like, "Whenever anyone is talking to you.")