Zayn: He loves when you bite your lip. When your thinking hard or laughing or just out of habit. He thinks it's absolutely adorable, and sexy. It makes him want to kiss you more than he does normally. (Which is a lot.)
Liam: He loves when you whisper "Boo!" and pout when something goes wrong or something is mean. He thinks it's cute because your nose scrunches and your eyebrows furrow. It reminds him of Boo, from Monsters Inc.
Louis: He loves when someone comes out sarcastic to you, because the face you pull is priceless. Your eyes widen when the words come out. You then roll your head back, raising an eyebrow and curl your lips. It's a face full of disgust and he really gets turned on by it.
Harry: He loves when you sneeze. Weird, yeah. You have a cute, high pitched sneeze and you always blush afterwards because you get embarrassed easily. He always pinches your cheeks afterwards and you roll your eyes jokingly, another thing you do that makes him smile.
Niall: He loves when you giggle at something inappropriate. You guys could be sitting anywhere and when someone cracks a joke that shouldn't be heard, your hand flies to your mouth. You start giggling and Niall laughs with you, pulling your hand away from your mouth and kissing you.