A Rubidium Shake is a highly edgy and illegal drink, often containing narcotics and cheap alcohol. The target audience for this beverage was originally teenagers, but it is sometimes used by the older generations too.
"Boss? Are you drinking a Rubidium Shake?"
"NO! Wait... Am I? And also... Am I on fire? And why is that Unicorn licking Bill Gates?"
".... This is why you're not meant to drink a Rubidium Shake, Boss..."
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!