You should randomly assign call signs to the bots. Here's a nice website full of call signs you might use.

http://www.f-16.net/callsigns.html

My personal favorites (as well as a few I made up):

Alcatraz
Biscuit
Clam
Duck
Elmo
Fez
Headless
Gasm
Igor
Jester
Ketchup
Lumpy
Mandigo
Nugget
Omelet
Poet
Quizno
Rico
Scooby
Thump
Ursula
VAL
Wedge
Yak
Zulu

Your list of call signs should be stored in a text file so that you can easily create new call signs without mucking around in the code.