Their reaction of you kissing your friends goodnight.
Did I really just make this all Because of the image above? Yes, yes I did.

Izuku Midoriya:

Legit had to do a double take. I mean, you were walking around telling everyone goodnight before you went to bed since you decided to go to bed early. And that was normal. But it wasn't normal was when some of the girls asked for a goodnight kiss before you left for the 1-B dorms.

He snapped his head to you as he heard Mina ask you, and low and behold. You kissed her on her cheek goodnight along with a few other girls like Momo and Asui.

He has to snap out his his train of thought. And quickly started mumbling to himself if you had always done this and why he didn't notice this before.

Katsuki Bakugo:

Didn't really know you would kiss people goodnight. I mean, you kissed him goodnight all the time. At first he hated it, but now he was searching for you since now he couldn't go to bed without a kiss from you. He knew you hadn't left 1-A's dorms yet so he went looking.

Walked right into the common room right as you kissed Kirishima's cheek to tell him goodnight before you left. And man was his livid. He stormed over with his hands already sparking.

Luckily Kirishima managed to harden his body as you explained that you always gave everyone a kiss before you went to bed. Bakugo yelled at you, saying how he was the only one to get your goodnight kisses.

Tenya iida:

He knew that you would kiss people goodnight. It was one of the many things he observed even before you two started dating. Now back then he didn't really care. I mean, you would kiss him goodnight too.

But now since you were dating, he felt a little off about the whole thing. He knew it was completely platonic between everyone, but he still felt a little off about it.

Hell, even Bakugo asked for a goodnight kiss. Which shocked him the most. He watched as the hot headed classmate of his angrily asked for a goodnight kiss on his cheek and you happily complying.

Denki Kaminari:

He didn't really know you could kiss your friends goodnight. He only knew that you would kiss him every night before you left for your dorms. So when one night he was making his way to your dorms since you forgot his kiss he got a good surprise.

He walked right in after Rin let him inside and you were kissing Kendo, Pony, and Yanagi goodnight. The three of them happily kissed your cheek back too.

Now look, we all know that Kaminari is a bit of a perv. So the first thing he thought was. "Holy shít that's hot."
He didn't know that slipped firm his lips until it happened. Whoops.

Eijirou Kirishima:

He knew you kissed your friends goodnight. He thought it was so thoughtful of you to let your friends know how much you love them before you went to bed. And normally he always saw you kiss your female friends goodnight.

He will admit that he felt a large feeling of jealously and slight disappointment when he saw you kiss Tetsutetsu goodnight though. You were just giving him a forehead kiss.

But he insanely felt better once you strolled over and planted a nice long, loving kiss on his lips before you left to head to bed.

Mezou Shouji:

Shocked. Shocked and sad. He was making his way over to your dorms to return a hoodie of yours that you left behind and once he was let inside he saw you kissing Shoda on his cheek.

But thank god you noticed him and how upset he looked. So you quickly rushed over and explained everything to him with Shoda also confirming that it was completely platonic and it didn't mean anything.

Still is a little off about it. But now he knows that it doesn't mean anything. Plus, you always give him special goodnight kisses which he loves.

Tetsutetsu:

You and him both go around kissing all your friends goodnight. But you two always make sure to let all your friends know how much you mean to them. So normally ten minutes before curfew it would be spent kissing your friends goodnight.

"It's not gay if they have socks on." Tetsu would say, making you laugh as you both plant a single kiss on Kirishima's cheek with a small grin.

Meanwhile, class 1-A is staring at the three of you with weird ass looks.
"What the fuck." Bakugo whispers with the squad as Kirishima returns the favor to you both.