One of the funnier moments was playing EV in a group of 8. The tank put a target on himself and said "follow me, do not question", or something like that. As the floor was collapsing fighting Soa, the tank jumped to his death by mis-timing his drop and 6 lemmings followed him dutifully. The 7th lemming was watching it as we all fell one after another and the entire group was laughing about it, including the tank!
My favourite FP experience was when some guildies ( healer, DPS and myself as tank) queued for Kaon HM without pants/chest/gloves/shoes. 5 times in a row the random DPS did not say a word about it while we were all rolling around laughing. The three of us then all stripped for our next few HM Ops runs and no one else noticed until I put my clothes back on and the other healer commented on how little damage I was taking all of a sudden.
Otherwise it would be learning the Mentor fight in D7, or downing Bulwark pre-nerf. Those were a lot of fun.