To have an out-of-proportion vindictiveness toward someone or out-of-proportion desire to crush someone (metaphorically or literally). The person with the out-of-proportion feeling or the person on the receiving end of the feeling is usually male, but not necessarily so. Generally used with the preposition for.
God, Mark has a real hard-on for Eddie after Eddie got promoted over him.

That bitch, Katy, has a hard-on for Esther because she stole Katy's guy.
by dockrrrk October 19, 2012
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"Last party we went to had a bunch of bitch-beers and no hard A."
by shackledxdollie November 20, 2004
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Long Dong Silver could never get a real hard on, because his penis was so long.
by Jorge December 06, 2002
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When the penis is aroused and expands to it's full length
Kiersten : Mmmmmmmm! Mmmmmmmm!
Chad : Mmmmmmmmm! Mmmmmmmm!
Kiersten : I do love kissing you Chad and it makes you get A Hard On would you like a blowjob?
Chad : Yes Please!
Chad : Ahhhhhhhhhhhhhhhhhh! Ahhhhhhhhhhhhhhhhh! Ahhhhhhhhhhhhhhhh!
Chad : You know this reminds me of the other day when me and Jim were kissing we got Hard On's and took turns sucking each other's dicks!
Kiersten : Reallly I just gave you an amazing blowjob and your going to talk about your gay experience with Jim.
Chad : I'm not gay I'm bicurious!
Kiersten : Well sounds like your gay to me!
Chad : I gotta go Jim want's me to take A shower with him!
Kiersten : GAY!
Chad: Bicurious!
by SlopNChop March 07, 2017
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