Back in November 2009, ajax sent an email on IRC etiquette to Red Hat’s company-wide mailing list. This was long before my time at Red Hat, but fortunately Mark McLoughlin had republished it on his website for a while. He's now deleted that article, so I had to go to the Wayback Machine to find it again. I've had to refer several people to it over the years, so I asked ajax for permission to publish it again. He agreed. Here it is in all its glory.
From: Adam Jackson
Subject: On “ping” etiquitte
Date: Tue, 17 Nov 2009 12:21:30 -0500
IRC has developed a "ping" convention for getting someone's attention. It works because most clients will highlight channels in which your name has been mentioned, so something like
will make that channel show up pink instead of white for me 
I wish to correct, or at least amend, this behaviour. The naked ping should be Considered Harmful, for at least two reasons. The first is that it conveys no information. The recipient of your ping, like you, is a Busy Person. They may be in the middle of something requiring intricate thought, and should not be interrupted for anything less than fire, flood, or six figures of revenue. Worse, you may forget why you pinged someone; when, four hours later, your victim gets back to IRC and responds to you, you will be disrupted in turn trying to remember what was on your mind in the first place.
The second, more subtle reason proceeds from the first. A ping with no data is essentially a command. It's passive-aggressive; it implies that the recipient's time is less valuable than yours.  The pingee will respond in one (or both) of two ways. Either they will experience increased stress due to increased unpredictable demands on their time, or they will simply ignore naked pings.
The fundamental issue here is a misunderstanding of the medium. IRC is not a telephone. It's volatile storage. The whole reason the ping works is because the client remembers seeing the ping, and can save it in your history buffer so you can see who was talking to you and why.
The naked ping removes this context.
Please. Save your time. Save my time. Make all of our lives more efficient and less stressful. Ping with data. At a minimum:
ajax: ping re bz 534027
 – irssi 4 life.
 – Their time may well be less valuable than yours. That's not the point point.
See also no hello for more of the same idea.