A biscuit conditional is a statement that uses a conditional (if, then), but doesn't use it in a logically meaningful sense.
The classic biscuit conditional is "if you're hungry, there are biscuits in the cupboard." Of course, the existence of biscuits in the cupboard is independent of your hunger; if you aren't hungry, the biscuits are still in the cupboard.
Biscuit conditionals could generally be reworded as logical conditionals: "if it's raining, I have my umbrella" bares some resemblance to 'if it rains, then I'll use my umbrella'. However, this misses the point; biscuit conditionals are not warped conditionals, but statements of open options; you can be hungry and either eat or not eat the biscuits, if it rains I may or may not use my umbrella. The conditional is mentioning an option, not detailing a logical relationship.
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