I still remember it like it was yesterday. But the biggest betrayal I've had to date was when I first started playing hl2rp. It was i17, I was talking to some blacksuit under that house with the sewer exit. They sold me my first Greensuit but then said "Hey bud, you're going to need a Gasmask with that otherwise it's just a suit of armour". And I went 'Well, I'm fifty short'. And we both agreed to go hit up the ration terminal since that'd give me 50 tokens. They put their shit away because they were premium, I had to carry mine because I wasn't. Then off we went to get Rations.
While waiting in line I saw the Femchar, who I knew was the blacksuit, yelling at the Civil Protection saying they saw me leave RB6 with a Greensuit.
They became a Brown Tier loyalist that day, I was PK'd.