When to use touche?

Answer 1

Either when you are hit when Fencing - indicating that a point has been scored for the "touch" or during an argument when you just made a point such as 'you eat loads of crisps' and they may have said 'well you eat loads of chocolate' this would be a time when you can say touche - when you insult or make a point about someone or something and someone comes back by saying you do something similar or the same - thus "scoring a point" for their jab (analogous to scoring a point from a jab in fencing).

Answer 2

The term "touché" is used in fencing to acknowledge a hit by an opponent. It is also used in a more figurative sense to admit a good point made in an argument or discussion. It is normally used in response to a clever or incisive comment.