Try It Again Without Smiling--very funny account (by Ms. Francis, below) of working on TV commercials:--

"It took a while for me to realize that I was the happy model who had a close-up. I was meant to sit happily down next to the rap star, pick up a sausage that had been stabbed onto a fork, bite it, chew, discover how delicious it was, and smile.

It took me even longer to realize that a key sausage selling point was the audible crack the things made when you bit into them. To illustrate this phenomenon, one had to bite into the sausage with conviction, and deftly twist the fork down and to the left (but not out of frame.)

I was a vegetarian, but I think the most diehard meat eater would have been scared by the sausages. They were small and irregularly shaped, pale gray and studded with knots of gristle. They looked like boiled arthritic fingers. One member of the crew had been solely assigned to mopping up the copious amounts of grease that flowed out of the tiny horrors as soon as they were stuck onto the forks..."