The eating routine is firmly established. Kiddo gets strapped into her chair, the tray gets snapped into place, her bib is put on, then she gets some Cheerios or sweet potato puffs to keep her busy while we prepare her food. And at some moment in the eating process she pulls at her bib until the velcro gives, and the bib comes off. Then she looks at the bib, considering it, then she waves the bib around a bit, then she drops it over the side of the chair. A moment later she leans over, to make sure it's fallen to the floor. We can this learning about gravity. My dad calls it learning about anti-gravity, because most things that a baby drops get returned to them. I think for my daughter though, it really is gravity, because most things don't come back after being dropped.
This bib game does create the obvious problem of there being nothing to protect her clothes from her dirty face and dropping food. So we've added a clip to her ensemble. It only took her once to learn that the bibs aren't going anywhere any more, and she's stopped trying. But if the clip isn't put on... the bib is over the side, and gravity wins once again.