A shit meme copied from Viz, an English adult magazine. Spammed heavily on Pokemon Netbattle by a user named Drakodan. Used with deliberately "krappenshite" German to seem funny.
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!