Tips For Finding Rookie:

1. When tracking Rookie, make sure to check highly crowded servers. (Sleet, Mammoth, and Blizzard)
2. Keep in mind that Rookie is sometimes a bot and will not always repsond to what you say. 
3. Make sure to understand that for the April Fools party, Rookie will mainly be found inside the Box Dimension. Check out this picture I got of Rookie giving me a shout out! It was awesome.
4. Rookie changes servers every 15 minutes or so. He can also be on two servers at once! Keep your eyes open, and keep moving. Make sure to grab Rookies background when you find him too!