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8.
An individual who can actually reverse an erection. Someone sexually unattractive.

See also hard off
Oprah Winfrey is a boner-killer
by robin graves February 21, 2004
 
1.
(noun)- A person who says or does something so lame it immediately sucks all the joy out of a normally fun, hilarious and appealing situation.
"Yo man, enjoying the party?"
"Yea man!! Its fucking tight.. i ran over a dog on the way here"
"Dude... Why you got to be such a BONER KILLER!!!"

"Who puked on your pool table?"
"Just some Boner Killer."
by P. Lesiak December 18, 2007
 
2.
A girl so ugly and repulsive that when she walks into the room any guy who had an erection immediately goes flacid.
"Yo, I was at this party with all these chicks, but then this boner killer walked into the room, and I went completely limp."
by fallinouttadabox September 02, 2008
 
3.
A "BONER KILLER" is when something good is about to, or is happening and all of a sudden it turns out to be bad. Its another way to express your hopes being let down.
" I went to KFC and when i was in line, I saw a roach run across the floor. That was such a BONER KILLER.So I left."
Example 1: You meet a cute girl/guy. They stink.You all of a sudden loose all attraction.
Example 2: Your at a party and your having fun. Then some idiot decides to start a fight. It gets out of control, the cops come over, and you get arrested. Your night is ruined.
Example 3: You have a crush on someone and then you come to find out something terrible about them (i.e. STD, hoe, player, too many kids, married). Ruins the image you had in your head about them.
by Nick Diaz February 28, 2006
 
4.
One whose features make the erection process fail
Renee Zelwegger just killed my boner
by jabankyswirl June 01, 2005
 
5.
When you loose a hard-on
Like when your having sex and your mom calls wanting to know your sweater size.
by Erika December 27, 2004
 
6.
A person/thing who kills the mood when everything is going great.
Think of a situation going your way when a person just ruins it in the worst possible way. You then go, "Why do you have to be such a bonerkiller?"
by Mike_17 November 28, 2007
 
7.
When you are trying to get it in with your girl and one of your friends or siblings just happen to walk in the room and ruin the mood.
Guy: So babe, Whatcha wanna do tonight?

Girl: Well I was thinking maybe we could...

Sibling/Friend: Hey guys hows it going?

Guy: Damn, You Boner Killer
by KingRydah February 28, 2011