Why you should react.

Its not really a safe world. Especially when you are in a place where eve-teasing has become the most common thing that could happen on road; when people stare at you when you get teased and walk away in peace.Well it is a whole lot of open thinking present in the world.

 Then someone advices not to speak back or respond haughtily to hooting and comments because you don't really know what they could do next. Keeping aside that this 'they' is just another person who has a misplaced version of acceptable behavior, I think there is a reason why you should react. Why you should tell a teaser to stfu.

No one grows just by night into this mentally sick idiot, who thinks passing snide comments or molesting a woman is normal or entertaining.

 So you don't face the highest version of sickness right out. It starts with a teenager on a cycle, along with his friends showing off that he can call out names to a random girl. Now you either smirk at him retort bad, or get embarrassed and try to dust it off. 

You would receive advice from your friends or family to just get out of the place. But have you realized what happens when you do that? The teenager who for the first time has made cat calls to show off in front of his friends has indeed become a showoff as you have not retorted and embarrassed him in front of his friends. 
Had you embarrassed him, every time he has an intention to carry out the same act ever again, he will remember this embarrassment and would not find it amusing anymore. When you do not say anything, you make him a hero (well, the group at least will be impressed by his guts) and so he will be continuing this behavior. Not only this, some shy and not so participating guy might find this inspiring enough to try catcalling because it gives him attention.

Maybe this is the reason why you should react! Not only because you have a right to be, but because you are actually doing more than that.