There are a few ways to check your in-game ping in World of Warcraft Classic. The first is to simply type "/ping" into the chat window. This will cause a small ping meter to appear in the top-left corner of your screen, showing you your current ping. You can also check your ping by opening the "Network" tab in the "System" menu. Here, you'll find a more detailed breakdown of your current ping, as well as your latency.