1000+ Buddies

Step 1: Have 999 buddies, and then buddy more than 2 people who are offline.

Step 2: When the 2nd buddy accepts, they will be your 1001st buddy.

The 2nd buddy causes you to have -1 buddy slots remaining. If a 3rd offline buddy accepts when they log on, you'd have 1002 buddies, and you'd have -2 buddy spaces remaining, and so on.