Spongebob Squarepants - Wow, Patrick Has a Lot of Armpit Hair...or Does He?
In Rock-A-Bye Bivalve, when Patrick says "Just call me daddy!" he has a lot of armpit hair, but when he watches T.V. later on, he doesn't, even though he still raises his arm!
Spongebob episodes do things like this all the time. they are constantly changing their appearance for effect. This is not a slip up since the artists and writers definatly did this on purpose.