The delicate moments right before one really, really has to take a shit, where the shit is literally poking its head out of the sphincter then quickly hiding inside again.
For turned based strategy games, it means to keep your units together usually in or near their default positions on the map and use defensive tactics such as attacking only when the enemy is near you, using defend commands or other units to defend each other, etc.
In fighting games, it means to keep defending and block all of your enemies attacks untill there is an opportunity to strike.
Basically, in both cases it's using defense/blocking untill you have a good opportunity to make an action or attack your enemy.
"I just beat Nightmare Geese in Real Bout Fatal Fury! He was tough, but I blocked his attacks with my turtling skills and then attacked when I had the opportunity."
"In Front Mission in the 2nd or so battle against Driscoll's forces, I turtled and didn't move my units then attacked as soon as the enemy came near by"
The act of the male penis shrinking in horror and retreating into the abdomen whenever danger is present or a very unpleasant, anti-arousing thought is experienced. Much the same way a turtle retracts it's head into it's shell when faced with danger.
(v.) The act of taking one's backpack, emptying the contents, flipping the backpack inside-out, putting the contents back in, and zipping the backpack up.
The act of turning one's backpack inside out. Typically done to a classmate when he/she is zoned out, or just very involved in the lesson that day.
A very funny practical joke, that will be appearing in the 2014 Olympics as Speed Turtling.
Usually done by ninja-like people, who are adept in the art of stealth. If the turtlee happens to catch the turtler in the act, the turtler has to return the contents of the backpack to their original state.
*reaches for a pencil* "Dude, what happened to my backpack?"