Zefta is an arabic (jeddawi) word used to describe people—girls in particular who you might be mad at, and is sometimes used during arguments as an insult. It can also be used as a term of endearment between friends.
A hardo is a person who tries extremely hard at everything. Most times a hardo will try very hard at things that do not require excessive effort. For example, sports practices, gym class, etc.
Wow did you see Jack at practice today? What a hardo!