kacknerd
A kacknerd is someone who talks too much and doesn't know what they're talking about. They're like a broken radio that only plays static.
My neighbor is a kacknerd. He talks nonstop about his cat like it's the president.
At the mall, the guy next to me was a kacknerd. He bragged about his video game skills but lost to a kid with a broken controller.
My mom called my brother a kacknerd because he tried to explain quantum physics to a toddler.