Dunning-kruger

"It's only been three months, and Tom is saying he's fluent in French already." "Nah, he's just at the summit of Mount Stupid." "Mount what?" "Look up the Dunning-Kruger effect."

Source: tatoeba (9696540)

It's a good thing I don't suffer from the Dunning-Kruger effect.

Source: tatoeba (10145037)

So while in the throes of Dunning-Kruger and Advanced Beginnerism, they're being given Expert-sounding titles and told that they're rock stars and ninjas by recruiters, especially in today's economy.

Source: wiktionary

And this is the second important piece of Dunning-Kruger. When asked if they know how a toilet works, many people will often say that they do. But when asked to describe how it operates, many are incapable of explaining it.

Source: wiktionary