SpongeBob and Sandy are practicing karate against each other. SpongeBob is carefully going around his house looking for her, until she jumps out. They fight, and have a lot of fun. Sandy threatens SpongeBob with a drop of volcano sauce (that talks) to the tongue, and tells him that she will sneak up on him and fight him tomorrow. At The Krusty Krab the next day, SpongeBob thinks anyone or anything can be Sandy, so he is cautious and does not work much. When he strikes one of the customers, Mr. Krabs demands to know what is going on, so SpongeBob explains to him that he is doing karate.
Therefore, Mr. Krabs tells him to stop doing karate, or he will have no choice but to fire him. Later, Sandy attacks him, and though SpongeBob attempts to explain Mr. Krabs' warning, Sandy does not believe or listen to him. At that moment, Mr. Krabs sees this and thinks he is doing karate with Sandy. An angry Mr. Krabs comes out of The Krusty Krab and tells SpongeBob that he is fired. This upsets SpongeBob and makes him cry. Sandy quickly explains to him that SpongeBob tried to tell her, but she would not listen. Mr. Krabs gives SpongeBob his job back. Mr. Krabs warns SpongeBob not to do anymore karate as he feels that it is poisoning his mind.
The two attempt to forget about karate, and go to the park. However, while slicing sandwiches, they begin doing karate again, Mr. Krabs catches them again. SpongeBob admits the truth and explains that he cannot help himself. He gives Mr. Krabs permission to fire him. However, instead of firing SpongeBob he finds that karate chops can replace knives. The next day, Mr. Krabs has SpongeBob and Sandy slice Krabby Patties using Karate, and in the end it earns Mr. Krabs more money.
There is a fish fishing for fish with a fishing pole at the Bikini Bottom Park.
When SpongeBob attacks Fred and sends him into the floor, some fish are shocked. One of the fish (who is gray with something purple on his face) is the fish that acts confused when he hears Plankton's squeaky voice in "Walking Small."
The face on the hot sauce drop is Tom Kenny's face. In the Season 1 DVD commentary, he stated that he had to wear red makeup all over his face in order to make the hot sauce scene better.
Kenny also stated that the scene was shot in the Nickelodeon restroom, and he had an audition later that same day the scene was shot, and the red makeup would not come off fully.
Two clips of this episode was featured in the 2010 film, Date Night.
In this episode SpongeBob is a karate master like Sandy. However, in other episodes, SpongeBob is much less skilled.
This episode includes a rare instance in which SpongeBob defeats Sandy in a karate fight.
The mask that Sandy says is her "worst disguise yet" looks extremely similar to the one that SpongeBob wears when he pretends to be Sandy's "pappy" in "Sandy, SpongeBob, and the Worm." The only difference between them is the colors.
The hot sauce drop is notable for scaring younger viewers due to the live-action face and the fact that it shows up out of nowhere.
It has also become an internet meme.
This is the only episode to date to show Sandy in a nightgown without her breasts showing.
It is unknown if Sandy and SpongeBob ate the Krabby Patties because after fighting, (and making Krabby Patties) they were relaxing and the Patties were still on the ground.
The fish shown on SpongeBob's T.V. is a royal gramma (Gramma loreto), a tropical aquarium fish.
SpongeBob thought Sandy would be in the restroom, meaning that either the Krusty Krab has a unisex restroom, or that SpongeBob was still thinking Sandy could be anywhere around him.
This is the first appearance of volcano sauce. The second is in the episode "Nasty Patty."
In the Japanese dub, this episode is called "空手大好き," or "I Love Karate."
The volcano sauce drop is dubbed over by Keijin Okuda. He's the Japanese voice of Mr. Krabs, Patchy, Larry, and the narrator.
A short clip of SpongeBob crying from this episode was featured in the music video for "Hallelujah Money", a 2017 single by British virtual band Gorillaz .
SpongeBob's lying on the ground opening arms in and out saying "photosynthesis" is a reference to how stomata provide gas exchange (for tasks such as photosynthesis).
SpongeBob leaves the kitchen with a tray of six Krabby Patties. When he tosses the Krabby Patties onto Squidward's head, all six stick to Squidward's head. In the next shot, there are eight Krabby Patties. In the final zoom shot of Squidward's head after SpongeBob says "Nice hairpiece, Squidward," ten Krabby Patties can be seen.
When SpongeBob is cutting the food, on his first cut, the mustard seems to disappear.
Spongebob's arm disappears when Sandy hangs up on him after his attempt at phone karate.
Oddly, during the fight between SpongeBob and Sandy, a brick can be seen in their dust cloud.
When SpongeBob slices the first slice of salami, the mustard bottle is missing.
A second window was added to SpongeBob's pineapple home near the lower right corner. Before, there was only one window on the upper left corner.
After the volcano sauce threat, Sandy karate kicks SpongeBob into the background. SpongeBob yells "Curses!" and Sandy appears to be moving her mouth as though she is also saying it, though she could be mimicking it.
Mr. Krabs tells Squidward that he was in his office, however, the viewer will notice that Mr. Krabs' office is the first door on the left, and when he comes in, he is on the right. But when SpongeBob talks to him, Mr. Krabs is on his office side, next to Squidward.
When SpongeBob rolls Sandy into a ball, her helmet disappears.
When SpongeBob goes into the restroom (of the Krusty Krab), there is the "Please wash your fins" sign on it. Later, when SpongeBob is walking, it disappears.
In the scene with SpongeBob holding the rock together to hide it from Mr. Krabs, a "tree" can be seen in the background chopped in half. The "leaves" of the tree are also chopped in half, even though they would not be touched just from chopping the tree in half.
In the scene with SpongeBob capturing Sandy with the Novelty Toy Tongue, she has her left arm inside her suit while she guzzles down hot sauce. Once SpongeBob loops the tongue around her, her arm immediately appears outside of the suit.