have (something) against (someone or something)
To dislike or be opposed to someone or something. A specific thing does not have to be stated between "have" and "against"—words like "something" and "anything" are commonly used there. A: "I knew you had something against Janet!" B: "She just irritates me, that's all." The board didn't have anything against my proposal, so I'm allowed to start working on it now.
have something against someone or something
to have a reason to dislike someone or something. (Note the replacement for something in the negative in the example.) Do you have something against me? I have nothing against chocolate ice cream.
have something against
Be opposed to, especially for a particular reason. For example, Do you have something against this plan? or Annie must have something against Mary, because she's always so surly when they're together .