So called "3rd Party Outings" are when the soldier in question does everything within his/her power to keep the orientation secret (as the rule requires), but someone else finds out that person is gay, outs them to the military, which then has to discharge the person in question. Thankfully it's rare, but not rare enough:
The Rapid City Police Department says Newsome, an aircraft armament system craftsman who spent nine years in the Air Force, was not cooperative when they showed up at her home in November with an arrest warrant for her partner, who was wanted on theft charges in Fairbanks, Alaska.
Newsome was at work at the base at the time and refused to immediately come home and assist the officers in finding her partner, whom she married in Iowa - where gay marriage is legal - in October.
Police officers, who said they spotted the marriage license on the kitchen table through a window of Newsome's home, alerted the base, police Chief Steve Allender said.
Got that? Jene Newsome at work at her air force base. Police showed up at her house and asked her to come home to let them in. She said no, she had to stay at the base. Police started peering through her windows, saw a marriage license on the kitchen table (seriously!?!), and decided this was absolutely vital information that the Air Force base just absolutely HAD to know.
And now Newsome's lost her job. Wonderful.