What is Boner-killer?
1.
One whose features make the erection process fail
Renee Zelwegger just killed my boner
2.
An individual who can actually reverse an erection. Someone sexually unattractive.
See also
Oprah Winfrey is a boner-killer
3.
Somthing or somonethat kills the fun that you are having
Guy1: Yo Stop screwing around!
Guy2: (to some1 else)Geeze, what a boner killer