It's that sort of behaviour that worries me about any form of biscuit competition. Fair play to you, however - a punch is clearly the way forward. Favourite crisp would make a similarly excellent world cup, with unfortunately very similar pitfalls. Your brother-in-law would probably foolishly...
Another vote for a Biscuit World Cup, but biscuit definitions would have to be CLEARLY defined. We cannot allow things like jaffa cakes or anything that might pass as a chocolate bar or cake. It's a slippery slope.