If they can't ignore it without a password, then they won't ignore it with such a simple password scheme either. The advantage of a riddle style password would be that it'd be technically fair (in that anyone who can answer the riddle, which is publicly posted) can get into Wibbles. It'd also allow people to easily invite people they want to have in Wibbles into Wibbles, while still allowing a little bit of exclusivity. It'd also allow people who want to be deterred from Wibbles to get a fresh chance at being deterred from Wibbles each month. That's my reasoning for it.

My reasoning against it is "Wow, that could breed a lot of elitism", but TP is somehow fine despite its even more inherent possibility for elitism, so... maybe that's not a problem?