Vinayak Manoji

Once teacher pointed towards student with her ruler and said:
“At the end of this ruler there is an idiot!”
Student: Ma’am which end???

Lakshay Gautam

One of my teachers told us how he had retorted to his own teacher at the end of a heated debate-
Teacher- So you think you know more than me? Son I have 1000 times the knowledge you have.
Student- Sir. My knowledge is zero.
*Teacher leaves the lecture hall*

Avinash Bhawnani

Teacher- Whoever will give the right answer to my next question can go home.

Teacher- Who threw that bag?
Rocky- Me. Now I am going home.
Read somewhere on facebook.

Raam Sridhar

This isn’t exactly a comeback but it’s sort of in the same tone as most of the answers here.
So here goes nothing..
We had this really annoying teacher (T) whom, naturally none of us liked. So this one day, he picks on my friend (F) and what began as a telling-off for talking in class or something (I don’t really remember) turned into a casual chit-chat in a tone that our entire class could hear:
T: Why don’t you sit quietly in class?
F: (diplomatic silence)
T: What’s your father?(Implying, “What is your father’s occupation?” This is a means of judging a student, and an often sought after ground to advise him/her on)
F: He is an electrical engineer sir
T: Oh, where did he do his engineering?
F: At Anna University sir(A prestigious University in Tamil Nadu, India)
T: Oh, just like me!!
F: (After a pause) No, sir, he really studied at Anna University
Needless to say, the whole class burst out laughing.

Alan Bell

A linguistics professor was lecturing to his English class one day. “In English,” he said, “a double negative forms a positive. In some languages, though, such as Russian, a double negative is still a negative. However, there is no language wherein a double positive can form a negative.”
A voice from the back of the room piped up, “Yeah, right.”

Imran Khan

TEACHER: George Washington not only chopped down his father’s cherry tree, but also admitted it.Now, Louie, do you know why his father didn’t punish him?
LOUIS: Because George still had the axe in his hand.

Chris Bishton

My sister’s mate at school got told, ‘You must’ve been at the back of the queue when God was giving out brains.’ She replied, quick as a flash, ‘At least I was in the queue.’

Niranjan VK

Teacher: ‘Nihal, you know you can’t sleep in my class.’
Nihal: ‘I know. But maybe if you were just a little quieter, I could.’

Thomas Mono

Most embarassing comebacks I’ve heard in highschool:

Teacher: “Pay attention Andy, or you’ll end up being a garbage collector.”
Andy: “Sir, my father used to be a garbage collector. Is there anything wrong with that?”
Teacher, flushing: “Errr… no of course not. But you could be a doctor or a scientist instead. Don’t you think your father will be very proud of you?”
Andy: “Sir, my father died last year.”
(EDIT: Don’t feel sorry for Andy too much. I should have mentioned that Andy was a smart but cynical kid, only demonstrating to the teacher the nasty potential of the risks he was taking. Andy’s father was neither dead nor a garbage man at the time.)

Rahul Sindhwani

Teacher: “Anyone who thinks he’s stupid may stand up!”
*Nobody stands up*
Teacher: “I am sure there are some!!”
*Little Johnny stands up*
Teacher: “Ohh, Johnny you think you’re stupid?”
Little Johnny: “No… I just feel bad that you’re standing alone…”

via Quora