Ragnarok: If anything, your bad breath will scare him into a full-blown coma!
Maka: I don't have bad breath!
Ragnarok: Yes you do. It smells like pork and fruity chapstick.
Ragnarok teasing Chrona when he's trying to write a poem to express his feelings for Maka.
Ragnarok: (mimicking Chrona) Ohhh, Maka. You make my soul all wet. Come heal my little broken brain with your magical rays of lovey goodness!
When Stein tells the class that Ox was the only one who got an A on the last test, the Insufferable Genius immediately whips around to shout to Maka, "Suck on that!" He is promptly Maka-Chopped.
Combined with Heartwarming Moments - Black Star giving Chrona a huge bouquet of flowers as an apology for upsetting him earlier (he still thinks Chrona's a girl).
Ragnarok is full of these -
Ragnarok: Ugh! If you drag me to that dance and then just stand alone in a corner the whole time feeling sorry for yourself, I swear I'm going to grab your ears and stretch them out so far I can tie them in a knot!
Ragnarok trying to get Chrona to hurry up getting ready for the dance by helping him out in the shower, a la Kid and Kim in Chapter 98 of the original manga. And then there's him getting excited about a possible Panty Shot from Tsubaki...
Black Star: B-because - two girls, and they were - but...Aaaagh!(runs off into the woods)
Chrona: What just happened?
Soul: I think he blew a fuse in his brain. Happens sometimes.
There's one from Maka and Chrona's otherwise very heartfelt and emotional love scene - Chrona being introduced to oral sex, something he is entirely unfamiliar with.
Chrona: Y-y-you...You licked me.
Heat flooded her cheeks. His reaction made her wonder just how innocent he was. Even if neither one of them knew much about it, surely Chrona had at least encountered the concept of oral sex.
Or maybe not. He was looking at her as though she'd just informed him that she was actually a mermaid from the moon.
When Blair congratulates Chrona and Maka on, ahem, getting together, she gives them a big hug and unwittingly puts them both in Marshmallow Hell, and Ragnarok takes the opportunity to take a look at her cleavage.
Spirit: (while shaking Chrona and crying) Don't ever break her heart! Don't make the mistakes I did! Give her all your love! Even if you have to wear a chastity belt and hang the key on a golden chain around her neck!