As for the cat thing, try to at least get it put down if you have to, shooting it sound so.... white trashy.
Anyway, for events I always remember Trickster to have great ones, but for halloween I'd suggest you play the FFXI trial. I'd never had more fun in a halloween event than on FFXI. If it absolutely has to be free, there's a graphical mud called Wyvern (
www.cabochon.com) that hosts amazing events for halloween, but you may not be interested as it is a very complex game.
F2Ps don't really offer fun holiday events; they are usually kill X monsters and get a pumpkin hat or something :/.