On toffee, and dancing.

On Christmas Eve this year, a date that already seems remote, we listened as usual to the King's College carol service on Radio 4 and, as the short day darkened, made toffee.

This can be a fraught affair - slabs of chocolate must be carefully broken up, nuts crouched; temperatures and timings must be finely calibrated, complex blends concocted then poured and quickly spread on chill marble. It sets very quickly then another layer is added and so on, before melted chocolate is poured over the whole lot and crushed nuts and suchlike added. Soon after it all has to be carefully levered away (or 'spatulated' as we call it) from the slab and broken up into irregular fragments, then boxed. It takes about two hours in all, after which stiff recuperative drinks are called for  and it's all over for another year.

All of which prompts a question: why is at that we describe somebody's ineptness at (for instance) dancing with the phrase "he can't dance for toffee"?  I looked up the idiom and it's orig. is obsc. and I can't help wondering why toffee should be taken as a measure of incompetence. Making toffee requires confidence, organisation, split-second timing and reckless daring.