I'm just wondering if it is safe those who are giving free coins asking for private keys, and saying that it is safe they don't store it?
The usual sample is asking you your ETH balance, then a certain coins balance, and it will generate how much coins you will get based on your ETH and a specified coin balances. Then they will ask for your Private keys.

I just passed by all this coz I don't want to compromise my wallet for few tokens.