Snarf is napping in something. It turns out to be an alarm horn on one of the castle's outer walls, which suddenly blares, waking him up and he ends up falling head first into the castle's moat, screaming all the way.
The Thunderkittens get one when they pick the pocket of that Jerkass using Wily Kit's Hypno Trinket.
Jerk Cat: Your music is as lovely, as the day is long...
In "Ramlak Rising":
Wily Kit and Wily Kat mewing and pleading like, well, kittens to get Lion-O to let them join him.
In "Journey to the Tower of Omens," ** Cheetara offers... encouragement as Lion-O is attempting to use the Sword Of Omens' sight-beyond-sight. The Thunderkittens promptly tease them ("I know what they were doing!") and Lion-O protests that they were just trying to get his sword to work.
The race in the opening minutes, especially the way Lion-O starts off before Tygra can finish counting, and how Cheetara and Panthro both join in, the latter after much goading from the former.
The first exchange between Lion-O and Aburn, and Aburn can't remember anything for more than three seconds.
Also, Wilykat's expression during this exchange is priceless.
Wilykat: Where're you going?
Wilykit: To meditate!
In "The Forest of Magi Oar"
When Lion-O is in the clutches of the not-so-evil giant bird Viragor.
Lion-O: You're gonna eat me aren't you?
Viragor:...Thinking about it.
The scene at the campfire: Panthro is once again snoring raucously, causing Tygra and Lion-O to ruefully agree that he sounds like the Thundertank and he's as bad as their father was. Which leads into Tygra claiming Lion-O snores just the same, and that this is the only thinghe inheritedfrom Claudus.
From "Into the Astral Plain".
The very small bit with Aburn
Aburn: Hello Kit! (fails to realize he's ruining the Cats' plans and starts waving) Oh, and you brought your friend Linus too!
The continuous mention of the spirit stone being in the hut and Grune's growing annoyance of being told that.
The look on Gune's face after the elephants thank him for blasting one of their trees!
Grune: Excuse me!?!
In "Between Brothers," Grune suggests to Slithe that they betray Mumm-Ra while he's in the Astral Plain. Slithe points out how powerful Mumm-Ra is and asks if Grune would really betray him. The way Grune just grins in response is chuckle-worthy.
"New Alliances" gives us the various attempts by the Robears to give Panthro new arms. Seeing a big guy like Panthro with lil Robear arms just can't be unfunny.
When he does get the right arms, he uses their stretchy/extending abilities to sucker punch Slithe, Kaynar, and Addicus. Whether or not you like the new arms, the surprised faces the generals make upon being punched are hilarious.
The opening of "Native Son" has Lion-O get a little mischievous and throw a snowball at Tygra. Tygra scolds him a little for acting childish, cue Lion-O throwing another snowball at him while his back is turned!
In "Survival of the Fittest," upon being handed two sticks to hunt with, Kat assumes Cheetara and Panthro want him and Kit to fight to the death.
Panthro: You know what?! It's about time you learn some hard life lessons!
Kat: HE'S GONNA KILL US!!
Kit: I told you he would!
From the same episode, when Kat is reluctant to let a cute animal fall into their trap:
Panthro: That is a meal. The cute ones taste the best!
From "The Pit", while the gag "They look like they hate each other but are actually friends" is classic, Tygra and Cheetara's flabbergasted expressions sell it.
Tygra: They're... friends?!
Cheetara: I can't tell...
From "The Curse of Ratilla," Lion-O, Pumyra, and Panthro have been captured and are about to be executed. Lion-O assures Pumyra that he'll get them out of this and as the executioner gets ready to kill Lion-O, Panthro speaks up:
Panthro: Maybe you should start with me. He's got to get us out of this.
There's also Lion-O's face when Pumyra suggests he "Move on to someone else." Keep in mind that this is the same girl who tried to kill him only a few hours earlier, the poor guy has no idea what's going on!
Tygra: (to the dinosaur-looking evil beast, while flapping his arms like a mad man) Instead of fighting, let's talk about our feelings!
And while Tigra is under the effects of the potion, he calls Panthro a silly goose.
Cheetara:...Did you just call Panthro a silly goose?
Tygra's reaction after he recovers from the love potion is comedy gold as well.
Lion-O: How do you feel?
Tygra:: (annoyed) Like you look.
Lion-O: Then everything is back to normal.
And then the episode ends.
From the same episode everything in the scene where Lion-O completely screw up something as simple as giving a girl a flower
Pumyra: Aren't we supposed to be collecting firewood?
Lion-o: ... Oh! Yeah! I, uh, heheh... I didn't just walk you out here to get you alone... ahahah... ahem... (They get to work until she turns around and he shoves a flower in her face)
Pumyra: Is that supposed to be for me?
Lion-O: This? No! Yes... I-I just thought it smelled nice...
Pumyra: (takes a sniff only for the flower to squirt her with a purple liquid) AHHH! IT BURNS!
Lion-O: Ah... huh. Lemme take a look I'm sure it's justó (sees her swelled face and wheezes)!
Lion-O: Nothing! It's fine, you can barely tell!
Ponzi the potion maker, used to his customers chasing after him with Torches and Pitchforks, is unaware that one of his elixirs actually worked to ward off Mumm-Ra in his Nigh Invulnerable demonic dragon form when the Thundercats try to catch up to him to buy more of the stuff. All he knows is that they're giving chase in a huge tank, and when Lion-O tries to flag him down, he does so by swinging around the Sword of Omens while shouting for him to stop.
In "What Lies Above - Part One", Panthro takes their new aircraft, the Feliner, up for its maiden flight.
Panthro: Are we really that high up?! *screams*
Tygra: Don't tell me you're scared of heights!
Panthro: (covering his face) I didn't know until just now!
As the Feliner spirals out of control:
Pumyra: We're gonna die!
Kit and Kat: We're too cute to die!
From "What Lies Above - Part Two".
Lion-O: (sees only a single Fishman) ...And that's all you could find?
WilyKat: No, he just didn't like riding in here with the others. (he and Kit pull out the Foreverbag)