FUN ("F.U.N.")
SpongeBob:
What Is Fun? Let me spell it for you. 

F is for friends who do stuff together 
U is for you and me 
N is for anywhere and anytime at all

Everyone:
Down Here In The Deep Blue Sea! 

Plankton: 
F is for fire burning the whole town
U is for uranium --- bombs 
N is for no survivors, when you...

SpongeBob: Plankton! Those aren't what fun's all about. Now, do it like this. F is for friends who do stuff toget...

Plankton: Never! That's completly idiotic! 

SpongeBob: Here, let me help you. 

F is for friends who do stuff together
U is for you and me. Try it! 

Plankton: 
N is for anywhere and anytime at all!

Everyone:
Down here in the deep blue sea! 

Plankton: Wait, I don't understand this. I feel all tingly inside. Should we stop? 

SpongeBob: No. That's how you're suposed to feel. 

Plankton: Well I like it. Let's do it again!

SpongeBob: Okay! 

SpongeBob & Plankton: 
F is for frolic through all the flowers
U is for ukelele 
N is for nose pickin', sharing gum & sand licking here with my best buddy! 
Ha ha ha ha ha ha, ha ha ha ha ha ha ha, ha ha ha ha ha ha ha ha, ha ha ha ha ha ha. 

Mr. Krabs: Arggh... mutiny.