Images can be embedded in chat messages with HTML code

[zoozledl]

Also works with .gifs, can see this being easily abusable

 

[Amni3D]

Doesn't seem to work for video or audio, however.
While I think this is incredibly hilarious, I have to concede it grants us too much power, sadly >_>

 

[thusdonut0]

Yoooo, I was just about to post about this

 

[ethan8bit]

Can confirm it works. Thankfully haven't seen anyone using it for anything vile.