1. Getting the burning adrenaline buff on your hunter or warlock pet, dismissing them only to recall them in a highly populated area. . . such as the IF auction house. . . and killing all the low levels?
2. Kiting a Kazzak into Stormwind where he pretty much destroyed the place until a GM put a stop to it?
3. Summoning a raid group to the bottom of the world tree lake where they'd promptly drown.
4. Actually seeing Ivus summoned in AV. Mining rich thorium veins, blue drops from guards, and actually doing quests in AV to finally win after hours and hours of PVP.
. . . no wait. Not laughing at the last one. That was quite fun. Love classic AV.