This chapter was rewritten because, DAMN, my English was shit back then.
Masaomi:
You were watching Uta No Prince Sama (Or some other anime with a catchy song, also I have an Utapri Scenario book), when the song suddenly came so you immediately began to dance along and sing. Masaomi just chuckled, finding it rather adorable. When you ask if he wants to join, he kindly declined. He doesn't dance with you since he is a terrible dancer and doesn't want to look like an idiot in front of you.
Ukyo:
Sometimes while helping him cook, Ukyo will be listening to music and you will be dancing to it. At first Ukyo found it confusing and weird but now he will just chuckle and watch with a smile. When a slow song comes on, both will dance to it, forgetting that food is on the stove.
Kaname:
Sometimes while driving, some of your favorite songs will come on so you automatically will sing along. Normally the volume is high enough so Kaname can't hear your music but one time while singing, he suddenly turned it off and laughed at your embarrassed, shocked expression. While you hit his arm, yelling he is an asshole, he just laughed and said you have a good voice so you shouldn't be so embarrassed.
Hikaru:
He somehow knows everything that goes on in everyone's lives, and somehow sometimes even appear at a scene when he wasn't there before. So when you were singing and dancing to your favorite song like an idiot, did a twirl only to stop mid-twirl and quickly look at the door to see Hikaru leaning against it with a grin. He just chuckled and said he is so happy his boyfriend/girlfriend is such a dork.
Tsubaki:
Sometimes he will randomly storm into your room, sing a song before pointing at you so you will sing the next part than he leaves. It is weird but very fun. Whenever a good song comes on, both will dance like dorks to it.
Azusa:
He will sometimes catch you singing or dancing but he never reveals himself, not wanting to embarrass you. But he finds it very adorable and will stare while hiding.
Natsume:
Whenever a good song comes on a game, you will dance or sing with it just to annoy him since he wants you to just test the game and not waste time singing and dancing. So he will annoyed yell, asking if you can play the damn game.
Louis:
Sometimes while he is doing your hair, while sing some of his favorites songs than laugh when he sings along. Louis likes those moments, he finds them fun and wholesome.
Subaru:
Whenever he is at a game, while chant a cheer for him than laugh as his face turns bright red with blood running out of his nose. He loves to see you cheer him on and having fun yelling a silly chant you made up.
Iori:
Sometimes while watering the plants, will be humming a song. Iori finds it calming. Sometimes afterwards, he will give you a flower, saying he is your biggest fan.
Yuusuke:
He once entered your room to see you dancing around your room but his eyes were fixed on your ass and your hips swinging around. He cursed as his whole face turned bright red before closing the door and storming off to go fix his problem in his pants.
Fuuto:
He is an idol, of course he is gonna make you dance with him on his songs. You have seen him practice dancing so many times so you automatically knew the moves. He will laugh and laugh and tease you about how bad you're at dancing.
Wataru:
He loves to take your hands and dance with you to his favorite songs. He doesn't care who is watching, he is too busy having fun with you.