A "secret message" slash command

Whenever you send messages, everyone in the channel receives them on servers. What if a slash command allowed us to whisper a secret message to a custom person in the channel? I know there are DMs, but this command is faster than taking about 15 seconds going to DMs, and it just depends on how fast you are typing. The command is "/whisper <member>". The person who you've whispered the message to will receive the message as:
<user> whispered to you: [message]
That way, no one can see your message other than the person you've whispered to the message.