Send a Blank alert To Someone's Private

/roll targetusername

where targetusername is the username of the person who's private chat window you've opened. It will send a blank message

Example, if you open up a chat window to entente, and type code:
/roll naked.eye
he'll get an alert that you have typed something, while you haven't. The window will remain open. It's very useful for when you want someone to talk to you but don't want to start the conversation