Seeing the normally imposing Diablos Nacho running like a quivering coward after getting hit by a Frightgeist slug (which is what the Frightgeist slug does by the way) can make a person laugh.
The Slug Run
After Kord tries to convince Eli that entering the race is a bad idea, we then cut straight to the race venue, with Kord saying something along the lines of he can't believe Eli is doing this.
When Eli is in danger of getting flattened by one of the worm-monster-thingies:
Eli: I'm beginning to think Kord was right about this race. If we die, he's totally gonna rub it in our faces.
After Kord says that he'll eat his wrench if Pronto really did save the day, the look on his face after Eli confirms Pronto's story was hilarious, then his resignation and honoring his word caused a hilarious look on Trixie's face.
Shadows And Light
First of all, bear in mind that gold is the main currency used in Slugterra. When Locke tells Lode to imagine what they could do with all the money Dr. Blakk might reward them with if they succeed in their mission, Lode says they could buy heaps of gold.
Dawn Of The Slug
The security guy can get over-the-top in his desire to save the day.
Also, at the end, the security guy was about to give the Shane gang lifetime passes at the arcade but thinks they are too noble to accept it, to Trixie's annoyance.
Pronto's hilarious reactions to the advertising for Club Slug.
For that matter, the fact that the opening bars of the music in that commercial sounded a godawful lot like the Rick Roll.
When Pronto gets stuck in one of Stocker's traps, Kord's solution is to swing the cage until it's bashed open. Poor, poor Pronto.
After Kord gets hit by a tranquilizing dart, he tells the others not to worry since it takes a lot of those to knock out a Cave Troll like him. Cue the Enigmo slug everyone is after activating the trap that fires tranquilizing darts, which hits Kords with enough darts to knock him out.
Apparently, Kord likes playing pranks on Pronto. The Montage Trixie puts together could be watched on it's own for great laughs.
In a case of Skewed Priorities, Kord considers the bad guys making look him like a bad mechanic to be worse than making their mechas explode.
The pirate captain has a collection of his toenails. The looks on the Shane gang's faces...
Eli's original plan to bust Pronto out of jail involved a complicated trick shot. Viewers just know the plan is going to fail on the first attempt, so when it does in fact fail, we viewers can chuckle knowing we saw that coming.
Eli learning under Mario Bravado to learn how to pull of complicated trick shots have a few funny moments, like Eli accidentally covering Mario in pizza ingredients.
The New Kid Part 1
That big buff enforcer of Dr. Blakk falls down a bottomless pit, hits the bottom and says...
Shinai gives some of the disqualified competitors a less than graceful exit, with them ending up in a dazed heap.
Dark Water, Deep Water
Apparently, Malvolio Drake's brother, Brutale, is a bit of an idiot, as he has a grudge against Malvolio as he think he stole Mimkey from him. Malvolio points out that he gave it to him for his birthday, surprising him.
Malvolio loses Mimkey when a passing shark swallows it whole. The Stinger has both Malvolio and Brutale trying to find him by searching each shark and punching it out, over and over...
The Gentleman And The Thief
Dana Por managed to make the Shane Gang make fools of themselves when they tried to stop her.
The Running Gag of Kord trying to complete his crossword.
It turns out that Pronto's ancient molenoid tracking secret was just leaving a trail of crumbs, to his friends' disappointment.
Eli had to eat a bug to make sure Blite doesn't go crazy on them, Squick, maybe, but the look on his face and his friends' faces was worth it.
The Looks on the Gang's face waiting for Blite to finish his sentence.
Kord gets Eli and Trixie excited to go to a place to get the part they need and it turns out that it's a junk yard, to their disappointment.
The villains of the episode called themselves the "Tough Guys", which the Shane Gang found unoriginal and Trixie suggests "Scrap Force", and they accepted it!
The Scrap Force also aren't the brightest around as shown when one of them was fooled into ensuring his own side's defeat.
Boss Ember orders his men to go after the Shane Gang when they flee but one of them counters saying in a confused and questioning tone that the Shane Gang won fair and square, frustrating Boss Ember.
What Lies Beneath
Pronto's but caught fire, again.
Pronto: Some things never change.
Dr. Blakk says nothing can stand in his new train's way, only for one of his minions to say that there is in fact, somebody standing in their way.
Kord suffers many injuries but all he can say is that it's his best day ever.
Just the color commentary. One of them's named Vanderhuge for chrissakes.
Vanderhuge: "What the heck is that thing?!" Johnson: "I've been told it's a Slipsilver slug, transforms into a giant living ball of magnetised metal." Vanderhuge: "Just like my skull! If I hadn't thought of that when I was playing I might not have had to retire in broken-down shame!"
King of Sling
The Mood Whiplash when the townsfolk start cheering for the Ted Baxter apparently beating the Blakk Mooks (it's the Shane Gang of course) - and then immediately coughing from one of Pronto's Flatuorincus shots.
All the mishaps Pronto and Burpy go through to bust their friends out of jail, largely because of Pronto.
Pronto claims he'd 'getting warmer' as he sneaks through The Alcatraz... only to wind up in the kitchen. "In my defence, it is quite warm in here."
Keys To The Kingdom
The rest of the Shane Gang's reaction when they learn Pronto is the king of the Molenoids.
The reason why Pronto spent years running from his crown, one of the things he'd be required to do is fix everyone's broken plumbing and deal with everyone's petty problems.
The Molenoids in general are a dim-witted lot. Their species motto is even "Ignorance is Bliss". Their lack of a reaction to things they should have responded to are worth a few chuckles.
The duel between Pronto and the Ted Baxter has a beautiful one - both slingers pull perfect shots at each other, leading to the slugs casting bored looks at each other as they pass, like they know what's coming. The result? Double KO.
Just the fact that Pronto and that bugger can somehow de-pants each other during the duel. Which leads to Pronto winning by Squicking out the other guy.
The Thrill Of The Game
Pronto getting annoyed by the Game Master and wasting a slug on him, causing his friends to get annoyed at him.
Pronto got attacked by the slugs and ended up stuck on the ceiling. Apparently, it's a common occurence.
Eli: Couldn't agree on a movie again?
Eli and his slugs finding out what they just went through after their battle with the Cave Worm. The Slugs reaction of smelling itself is also priceless.
Eli: Were Gonna take some very long showers.
It Comes By Night
Pronto apparently doesn't know saving means not breaking mailboxes.
There's a Running Gag with airbags coming on after the point they would have been useful
Eli deliberately revved up his mecha so Blakk's words are drowned out.
Bandoleer Of Brothers
Starting of the episode including Joules shocked Banger while taking his food, Stinky lifting weights, and Bludgeon fainting from Stinky's smell.
The slugs antics were hilarious. Joules shocked Rookie, Chiller accidentally sneezed on Rookie and Spinner accidentally covered another slug with its web, for example.
Light as Day
Diablos damaged Kord's mecha beast. This made Kord's mad and Diablos suddenly looks less confident. The scene is worth a few chuckles.