Grab your egg-and-fours and let’s get the bacon delivered!
Oh, I don’t know. I think they’d assume the OP was being disrespectful and sarcastic if he just went around calling everyone “Admiral.” 
To get even more confused, see this thread which I opened some time ago asking about exactly when saluting is required, though that obviously wouldn’t apply to the OP since they are civilian. But it does give some background to the comment made by vetch. Based on the linked thread, where several military Dopers, both commissioned and non-commissioned, posted replies, a recreational football game would obviously be a “no-cover” situation when the usual honorifics were dispensed with.
I worked as a civilan federal employee for 5 years at an Air Force command center, and I called most people sir or ma’am, even enlisted (though usually just senior enlisted, say tech seargeant or above). Since most people were older than me, it just struck me as being polite anyway. I must say I was surprised when someone called me sir for the first time in my first few days.
For officers, I almost always called them sir, if I passed them in the hall, or <insert rank here> Lastname if I was addressing them. However, for all practical purposes, the lowest officer rank there was O-3.
In the daily workplace, I called all my co-workers, about a 30/70 split give-or-take of civilian/enlisted, by their first names. Our tech/development staff were either more senior civilians, or officers. I called the civilians by their first names, and the officers usually by their rank, though it depended on who it was. I wouldn’t hesitate to call them by first names too though, since I worked with them a lot. My direct supervisor was an awesome guy, master sergeant, and a few times I called him by his first name, and a lot of the other subordinate civilians did as well, so I think he didn’t mind either way from us. I usually called him rank/lastname though, and my coworker enlisted always did as well.
In summary, you can hardly ever go wrong with rank/lastname, or sir/ma’am if you don’t know. Personally, I wouldn’t have a problem saying the generic, "excuse me, how may I address you?
Funny anecdote: Before I was hired, I had an interview with my civilian supervisor (who later moved to the tech staff mentioned above). He liked what I had to say, so passed on to section chief (a Lt. Col at the time) his recommendation to hire me. Later that day he called me to formally offer me the job, and I referred to the section chief as Lieutenant Lastname (I did say I was right out of college, with no military experiences ever). He corrected me. 
There is sort of a related issue that is developing into a pet peeve of mine. It drives me batty whenever someone addresses, say, the U.S. attorney general or surgeon general as “General So-and-So.” They are not freaking generals! So the postmaster general is “General X”? Ridiculous. It reminds me of an episode of “Sharpe’s” in which the wagonmaster insisted on being addressed as “general.”
The Surgeon General is entitled to that title as head of the Public Health Service, one of the Uniformed Services of the United States. What, you thought Koop and Elders were just being pretentious? Well, they were, but that was also their real uniform and their real rank. Too bad they don’t have grooming standards to go with that uniform, because Koop’s beard looked like hell, but he was a General, so I guess he could do whatever the hell he wanted to.
The local Texas Army National Guard recruiting officer comes by my store pretty often, and I used to just avoid calling him anything because I knew “sir” was touchy if he was an NCO - I’d just be respectful without using a name or anything at all - but now I call him Sergeant or Sarge (since we’re relatively friendly) because he came in with his uniform on and I recognized his collar tabs. Staff Sergeant’s the only rank I recognize, of course, so it’s a good thing he IS a Sergeant or I’d still be nervously avoiding any honorific at all… The private that comes in when it’s the sergeant’s off day just has me call him by his first name after noticing me squinting thoughtfully at HIS shirt and trying to figure out how to address him. I got the impression that he found it rather amusing.
Not so. Don’t you remember that epsiode of Seinfeld where Kramer was taken into a back room where he received a talking to by Wilford Brimley?
I don’t know how true it is, but I read of a Lt. Col. at a big party of mostly civilians who was addressed as “Lieutenant” all evening by one matron. He was amused, but remarked he’d love to be around when she was introduced to a Rear Admiral.
DD
I don’t know it if is still the case, but Genral and Flag rank officers used to have the privilege of designing their own uniforms. This caused a bit of a flap in WWII. Eisenhower had an OD blouse cut off at the waist and made into a jacket, called an Eisenhower Jacket.
Well, guys liked the look and started having their issue blouses tailored the same way. This was a no-no on two counts, A) The enlisted blouses were government property and couldn’t legaly be altered and B) When they wore them they were out of uniform. However the practice got widespread and you can’t discipline everybody so the Army started winking at the practice and, I believe, finally gave up and made the jacket a part of the issue uniform.
It really depends on the unit and the officer. Many doctors and nurses are direct-commissions, which means they’re basically civilians stuffed into uniforms bearing absurdly high rank. Many of them don’t give a shit about military courtesy and call each other and their subordinates by first names. T(Think “Hawkeye”). This is fine in hospital settings except for the occasional friction when, say, a direct-commission captain calls a “real” major by a first name. Most people will quickly get over it when they realize who’s holding the other end of their enema. Sometimes the direct-commisssion officers. And sometimes, a direct-commission officer gets full of his rank and makes an ass out of himself playing Patton to lower-ranking officers with orders of magnitude more military experience.
This all changes in line units, what you’d consider “real” military units with tanks and guns and whatnot. Medical officers are vastly outnumbered by line officers, so standard military courtesy rules the day.
However, I’ve never under any circumstances seen anyone object to calling a doctor a doctor, whether on the giving or receiving side.
I just realized the above post is horribly written and I apologize. I hope the meaning is still clear.
Just as background for those who don’t know, when a doctor goes into the U.S. Army, regardless of the route he or she took to get there, the minimum rank is captain.
A close friend of my family “retired” from the U.S. Air Force as a full colonel before going into private practice. She’s just about as non-military as you can get in demeanour and personality, yet she was a colonel because she worked as a pathologist in the Air Force for about 15-20 years.
How about the nurses? Mom picked up 1st Lieutenant in the USAR Nursing Corps. I think she might have gotten out of school and into the military at the tail end of Vietnam, but I’m not quite sure of the timeline. (No, she never went overseas, though apparently she would’ve been sent to Korea if she had reupped. I think all her work was done at Walter Reed.) Is that a minimum rank as well?
Yes, I believe so.
Doctors and nurses go in as officers. As mentioned before, the minimum rank for doctors is captain. For nurses and PA’s, I’ve seen them bearing 2nd lieutenant rank. No matter where the source of your commission, promotion from 2nd to 1st lieutenant is mostly an automatic thing depending on your time in grade and the absence of any supreme fuckups on your record.
How do the doctors and nurses minimium ranks compare to someone coming in after college? Depending on how they joined, I guess.
A college degree in itself doesn’t guarantee officer rank, although it is usually required even to be an officer. There are many soldiers who have degrees serving as enlisted soldiers. I do think that enlisted college graduates are allowed to enter as a PFC rather than a private (E3 as opposed to E1).
The lowest officer rank is 2nd lieutenant. This is the rank at which everyone enters after completing an officer candidate program.
This is across the services, right? I mean, by pay-grades and not exact name of rank.