All Torn Up

Consider, for example, one of those soy sauce packets from the local Chinese takeout place.

When you tear a package open, you generally put your thumbs and forefingers together somewhere along the serrated edge in the packaging. (If you're lucky, your packet might have that little cut in it that's pre-started for your convenience.)

Now imagine yourself tearing that packet open, by gripping and separating your hands. Which hand tore backwards (towards your body) and which tore forward (away from you)?