Tagging DMs

Hey! I think it would be great if there was a tagging system we could use to organize DMs with others. This could also bleed into servers/group chats. Every time you search for

[tag denominator]<tag>

it would bring up posts that contain the tag.

Eg. 

(If we are to assume you can call tags with *)
We can now search for

*Dinosaur

to pull this message right back up.

Duplicate? Thoughts?