When is a biscuit not a biscuit?  When it's a cracker according to Tesco, who thus freed themselves from the obligation to honour my 40p off voucher.

Well there are plenty of dictionaries that will tell you that a cracker is a biscuit and vice-versa and had there not been a pressing queue behind me I might have engaged the cashier in a discussion of the Jaffa Cake case.

You will recall that McVities were anxious to have Jaffa Cakes classed as cakes rather than biscuits because chocolate covered cakes don't attract VAT while chocolate covered biscuits do.  The clinching argument of the eleven grounds on which the matter was judged was that cakes start out soft but go hard when stale whereas the life of a biscuit (as long as it's not eaten) follows the opposite direction.

Crackers go soft.  I rest my case.