kneel breaker 

An issue that arises on a date that ruins the romantic mood and terminates the possibility that the guy will be receiving a blowjob that evening.

We were heading back to my place from the restaurant and I jokingly said something negative about feminism that lead to an argument and ended up being a total kneel breaker.

kneel breaker by alt99 January 21, 2010

knee-breaker 

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!

knee-breaker by wickedpissa March 19, 2006

Knee Breaker 

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!

Knee Breaker by Pockets503 June 3, 2011