:ping
ping [<string>]
Replies with hopefully-useful information, including:
-* Current time, number of users on the system, and load average.
+* Current time, number of IRC and system users, and load averages.
* Most recent traffic on a relevant channel (if sent privately, any
channel we're both on, otherwise the channel in question.) Only
actual message traffic counts, and \!-commands don't count either.