For me it has to be just the other players that had mics i had So many good times just full of laughs. I loved to use combat axe and knives (i had about 5k kills with the ballistic knives) the reaction when i killed an enemy was always great, and just as great whenever looked at my most used weapon (the ballistic knives)
Spawntrapping in demolition with my friends & playing zombies till late night going for high round and making our own strategies (zombie train route) .