an ignorant and rude person
troglodyte - primitive
The word ‘troglodyte’ was originally used to describe people who lived in caves in prehistoric times, but has since been adapted as an informal insult directed at a person thought to not get out much and be ignorant of the world around them. Such people tend to have old-fashioned views on things and behave in a socially unacceptable way. Can also be used in a self-deprecating manner.
Luke really embarrassed himself at the party, insulting guests and acting boorishly. What a troglodyte!
Jane found it hard to adapt to the new office computer software because, by her own admission, she’s a bit of a technological troglodyte.
My teacher is very condescending and impatient with me. She treats me like I’m an illiterate troglodyte.