Well, the obvious answer is that it sounds like the product of mental illness, which is a) not something that we want to encourage people to shoot back at and b) can't really lead to good conversation.
The original comment was a joke, then? Because these are really the only two contexts it can be parsed with.
I took a look at your brief comment history. The amount of feedback you're going to get here will be increasingly limited as your comments won't even be visible to most users. So this could be the only opportunity to address you:
You might have a serious problem without realizing it. Please, if it hasn't been already, get it checked out.
I hope it didn't come across as me trying to diagnose you, because I obviously don't even know you well enough to say you have a cold. It's just, devoid of context, there's a really high chance that comment that sounds like that is a product of mental illness, and that's why people are prone to downvote them.
