My best LFR moment was actually back in Dragon Soul, as the image suggests, on Spine of Deathwing. There was an elemental shaman, either a bot or a troll, who kept killing all the Tendrils and spawning Amalgamations. I was tanking at the time, and the other tank and I were seriously fed up with this shaman, as soon as we'd zoned back in he'd start combat so he couldn't be kicked.
So we decided to roll. Remember, you never had to do that on LFR, only on Normal or Heroic, but we were being overrun by Amalgamations. We told the group we were rolling, explained in /rw how it worked, that everyone had to go stand on the marked player when we said to. We counted down, and everyone started moving to the left, stacked up pretty tight, and we rolled him.
And, miraculously, everyone had managed to get gripped apart from one player. The shaman. He flew off the back, and we took down Spine. Never have I been in such a happy LFR group, the GGs and congratulations and general feeling of elation that we'd managed to do it and lose the shaman was awesome. So how about you?