When joining a server, there is some lag. This is normal. But, you might try to type "H*e*llo", which is the following set of keystrokes: tHello. What happens? You open your inventory, despite pressing t first, as all of those are registered as happening on one frame. This isn't an issue when saying "Hi", as the command is tHi.

This is more of an annoyance on bukkit servers with a /server command, as you might type /server survival1 in the hub and end up opening your inventory anyways. It's an annoying timewaste.

This is easiest to reproduce by setting the framerate limit to 10FPS (giving you a 1/6th of a second window), and putting fingers over the t and e keys. Hit t and then e in rapid succession, and you will get the inventory screen (even though you can tell you hit t first).