Omaha callsign...
http://www.xmission.com/pub/users/g/glm/misc/milcalls.txt
biggest list ive ever found of military callsigns. go there. copy, paste and keep it all for yourself.
"Omaha" is US aircraft used in US customs/DEA activity.
each callsign is mission specific and given to various groups and wings individually. just like an individual airline
ie: "Orkin" is the rc-135's out of Offutt AFB Nebraska, 55th wing.
some fun ones ive seen on the list
PASTY-924th FW Bergstrom AFB,TX f-16's
DEATH-355th wing, davis-monithan AFB, AZ A-10A's
DAPPER DAN-94th aw, Dobbins AFB, GA
NIGHTMARE-some b52's use this and harriers from yuma,AZ too.
and supposedly Groom lake Nevada (area 51 fame) has the callsign "sperm lake" for anything happening there.