Jackpost
A person who is so full of hot air they think they're the center of the universe.
My uncle is a jackpost. He told me he had 'a million friends' and then asked me to be his 'special friend.'
My cousin's friend is a jackpost. She said she was 'a rockstar' but couldn't even play the guitar.
My friend's mom is a jackpost. She called me at 2 AM to tell me about her day.