Hi Swathi,
Hope you doing well!!
Good question swathi. Even i used to have this question at first days and by seeing people in my experience i have faced few situations were my pioneer and seniors used to poke me often to not to be so kind to the people and I was wondered why we cant?, why we should be rude or should carry serious faces to them though we can manage the situation. Later my experience thought me many things by that I can say 'yes' we can be rude at times, means "once in a blue moon".
I think you may wonder why? for this want to give two cases to make it clear
Case 1: We are interviewing hundreds of candidates daily. You might face some people with silly questions or in some people asking you such a question in which the question itself gives the answer and few just to get interact they irritate. specially Here try to be patient as much you can and you need to be. Being an HR the first quality is Humanity as in the the name HR itself says. We are here to give the best services (mankind) to the company, handling the situation even in any worst cases. Try all the ways to give your best while answering.
Case 2 : We will find people caring attitude and indifferent body language answering in rude way, here give them good answers but dont forget smile on your face, but at times this situations seems to be out of control means we feel impatient through we try to control in this case I say Yes we can be rude.
One thing we need to remember that situation differs with person to person. In most of the cases we deal the person as per our perception.
I have given the information from my experience. Please revert if you need any clarification on this.
Thanks & Regards,
SwethaN