When you see a hot guy or a hot girl, you'll break your knee to turn and look. Similar to a neck breaker, only this term could actually happen.
When Fallon was jogging on the path, she turned to check out a hot guy, and almost broke her knee." "That guy must have been a knee breaker!
by Pockets503 May 08, 2011
Taking a leak while sporting morning wood. To keep from spraying the wall, you lean forward as much as possible with your legs straight, to the point where you think your knees are gonna snap.
I had to take a serious knee-breaker when i woke up this morning!
by wickedpissa March 05, 2006