An abbreviation for the phrase "Nigga stole my bike!" The phrase originates from a Something Awful photoshop edit of a screenshot from the game Punch Out!! (particularly, a screenshot after a circuit) when Little Mac is running with his coach who is riding a bike, Mac is saying "Nigga Stole My Bike!" It became more famous from the site YTMND (www.ytmnd.com), where someone made a site containing the picture in question with a sound clip of a black man saying the phrase.
*erhem* Allow me to correct my friend up there. Or down there. Major spoilers for Perfect Kirby 3 ahead.
The hippin jippin gene is a funky (highly changeable?) gene found in only three people: Neil of the institute, Phill of the institute, and George W. Bush.
The crazy story about thinking Professor Oblivion created the hippin jippin gene to destroy the president stemmed from Roy's destruction of Professor 1.99's lab. According to Prof. 1.99's computer, when the hippin jippin gene is mixed with double-cherry Kool-Aid (which lo and behold, Professor 1.99 was experimenting with) creates strange results. It would have to be tested. So when the gene was successfully extracted from Neil, it was mixed with Double-Cherry Kool-Aid and tested on John Zerbes...it melted his skin and apparently the rest of his body down to the bone. Immediately they assumed that Professor Oblivion was out to find Bush and kill him.
But that was not the case. Roy was the culprit -- but he had no idea about the gene's killing powers. See, because the gene is funky, it means that Bush would be easy to control and clone. Roy was planning to make Bush declare him ruler of the world -- "..to rid the world of Professor Oblivion and his horrible coffee-making skills!"
Of course, you don't have to worry, because the story turns out good.
Of course, I haven't explained this fully. To obtain a full explanation, watch Perfect Kirby 3.1 - 3.3 at Newgrounds.