Cletus ticket drops from Cletus-GM spawned boss. Event was originally scheduled every 2 or 4 weeks, but due to being busy with real life, GMs can only host the event once in a while, I believe. It requires an extremely strong raid to kill Cletus. Cletus drops Ticket, pet, potion, shining trophies. If you can complete the quest, the reward is Cletus earrings. It requires you to kill an enormous number of monsters in PI, GTI and Lisk+Rhinestone statues. However, because of change in liskI, it's nearly impossible to finish the quest now unless you have a pro raid which I believe there is only one out there . For more information about cletus, you can seach nsDB or old thread about Cletus.

Thanks sir ^_^