Just a name I whipped up when I needed a username a while back. Been running with it for about a year.
Later I found out after I started learning Japanese, "Osu!" is Japanese for a manly/martial-arts "Yes/Sir/Yay" style of calling. Me and my Japanese friend always crack a smile when my other non-Japanese-speaking friends call my nickname in-game, "Oh-sue" which just is a horrible way to pronounce the original phrase. "Osu" is pronounced with heavy emphasis on the "O" with a short, quickly dying "S" sound that slips down into a silent "U". Hard to describe in text. It's like when a dog tries to bark, but stops--but if they are saying "Oh-sue" midway.