When a song is so good, it summons everybody to the dancefloor, when at a party or in the club.
A: "Dude, Everytime We Touch by Cascada is unironically one of the best songs of the 2000s. That shit is a floorcaller!"
B: "True, it's a certified banger."
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!