Spongebob Squarepants - Eyebrow, No Eyebrow! Eyebrow, No Eyebrow!
In the episode "The Suds" when Patrick offered to be Spongebob's doctor. He is about to fill Spongebob's holes with corks he says "It appears as though we’ll have to plug up these holes. This oughta do the trick." As Patrick says this, one of his eyebrows disappears, then reappears, then disappears again and then reappears again.