Exaggerate

After lesson...

M: Look at the eraser dust on the floor!
Ss A: Not mine.
Ss B: It's not mine as well.
Ss A: When I arrive at this place, I already saw the eraser dust on the floor.
M: You liar, I swept and mopped the floor before you guys come here.
(Ss A and Ss B are picking up the dust themselves.)
Ss A: The dust white in colour belongs to you. Your eraser is white in colour.
Ss B: Yours is black in colour.
Ss A: White..Mine...Black...Black...Yours
Ss B: White...White...Yours...
Ss A: In fact, all should be yours. I haven't erased anything today.
M: You are a big liar...That's impossible!