I used to say bisquits when I was a teenager and first learning english (at an american school so with an american accent).
Any adult that uses the word after having watched the advert is definately a candidate for a slap around the head with a wet fish.
I can't stand that advert, it makes me cringe. It was cute first time (ish) but now it is just bloody annoying.
And yes, 'simples' falls in the same catagory.