The expression is "hit the nail on the head," and it refers more to when someone says or does exactly the right thing, whereas "your cup of tea" is something that you just enjoy discussing. For example: He hit the nail on the head when he said the reason for the company's failure was lack of effective advertisement. You really hit the nail on the head with that analysis! “Did you hear that the boss is quitting?" "Is it because he had a big argument with the CEO?" "Yep, you hit the nail right on the head!" Here are some more examples: http://idioms.thefreedictionary.com/hit+the+nail+on+the+head Examples of "my cup of tea": "What do you think about the upcoming election?" "I'd prefer not to discuss that. Politics is not my cup of tea." "Do you think my sister will like this card with a cute puppy on it?" "If dogs are her cup of tea, then I think she'll love it!" "I don't know if sweets are your cup of tea, but I made you some blueberry muffins!" I hope that helps! Let me know if you have any questions :)

I think you've confused two idioms: "to hit the nail on the head" (a nail has a head, and no spots), and "to be put on the spot".

I think Mick hit the nail on the head when he said that what'slacking in this company is a feeling of confidence.

It's "hit the nail on the head" The head of the nail is the top bit which you hit with a hammer. I think the whole saying is based on how hard it can be to hit a nail correctly with a hammer.

We usually say "hit the nail on the head" instead. :)