Is the "Red two standing by" dialog in Star Wars: A New Hope sensible for real fighter pilots?
Tactical call signs are typically given in the format "word" "number" - "number".  For example, Camel 1-1.  In this example Camel 1-1 is the lead Camel in the Camel flight.  As you may have guessed, instructions are always acknowledged in order.  This helps the lead aircraft determine who may not have received the instruction (and some instructions are extremely time critical), or worse, in the event of an accident, determine (by lack of communication) who might be involved.  If someone does miss a comm, then typically the flight waits a few seconds and the next guy in line makes his radio call with the lead noting the person that was skipped.  

Tactical call signs change with each flight, and may or may not have any real significance to the event being flown.  Funny ones are usually best; i.e., Camel works really well if you want to Alpha check a point called "Toe".

Here's a typical scenario: While practicing a 2v1 in the MOA (military operating area), Camel 1-2 gets a HYD caution, and has to stop the fight.

Camel 1-2 initiates with, "Camels knock it off, knock it off."

Next the flight reports back in order:


"Camel 1-1, knock it off." 
"Camel 1-2, knock it off." (Even though Camel 1-2 initiated it, he still reports in order)
"Camel 1-3, knock it off."


I would say that Lucas came pretty close to replicating the actual sequence.  Sure, they're out of order and they're missing the "# - #" format, but its a decent attempt for Hollywood.