A disease transmitted electronically that affects, almost exclusively, young, immature females. It is characterized by repetition of (usually) the last letter of random words in a message, as if the infected does not have good motor control. Most often seen in texts and on Facebook.
Girl: "omggg i saw Justin Bieberrrrrrrr!!! (:"
Guy: "It looks like you have Keyboard Parkinson's, you should get that checked out."