Pretty much any short word relating to SpongeBob such as: happy and sponge.
Happy
One of the codes is "BUBBLES", another code is "PARTY", there are more, but I don't know them.
1234
Spongebob Squarepants
Why not
The SpongeBob Jellyfishing Mission Code is: savethejellies
spongebob
i <3 spongebob
click on spongebob
the code is jellybean
the code is presents
the code is valentine.