The word is actually "touché". It's French for "touch". As used in fencing, it represents scoring a point. Your definition is close, but no cigar; your spelling is atrocious.
a word used to express nothing to say after an insult? pronounced: 'to-shay'
If you are white and your friend is Mexican, you can say "You're a dumb mexican who mowes lawns", then your friend says "You're a dumb white slave owner", You would say "Toshay"