To be Smeckledorfed is the same as being tricked, fooled or bamboozled.
The term is a reference to the popular kids (and adults) show Spongebob.
If you pay for a 2$ item with a 5$ bill, and only get 2$ back, you have been Smeckledorfed, because the cashier kept 1$ of your change.
If your friend tells you that there is a surprise party waiting for you at home, yet when you get home there is no one there, you have been Smeckledorfed.
The term was first used in the Spongebob episode “The Nasty Patty” from season 3, aired 1st of March in 2002.
In the episode, Mr.Krabs and Spongebob are watching the news showing a man who pretends to be a health inspector to get free food. The person in the footage is the same man as the “health inspector” in the Krusty Krab at the same time. After short conversation, Spongebob says “We have been Smeckledorfed!”
Due to the artificial words’ silly nature, it was adopted as a synonym for similar words such as “bamboozled”.
Besides the numerous YouTube clips from the Spongebob episode, the term has been used as title for memes and short online stories involving someone who was fooled.