Oh hai guise! Or: Hai guise! is basically a Internet-slang/channey way of saying Hi guys! It's used a lot in Internet memes. (I don't know the exact origins so this definition basically needs modification.)
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!