1) To have cuts and scrapes all over the knee and shin area due to shagging balls during a game of dodgeball
2) Most often found on women as they tend to be the "shaggers", but it may also be found on men willing to throw their bodies around
3) Found often in Lister Dodgeball League matches
Greg - "Hey whats up with your knees?"
Kevin - "Oh, i was diving around alot today and gave myself shagger's knees"
Greg - "Gotta love Dodgeball"