A "drone" is generally a reference to an infection whereby your computer connects a "drone" (bot) to an IRC network which then automatically joins a specified channel, and it's controlled by the "botmaster". Once numerous people are infected there will be more drones, and they can be used to flood channels or DDoS websites/users.

If nobody were infected with trojans then the ability to DDoS would be crippled. So please not just now, but regularly in the future, check your system for viruses/trojans if you don't already and help the Internet in its struggle smile

A number of antivirus/firewall resources can be found in this thread.