Most simply, yogi-ing is asking other hikers for food, depending on whether the rules you hike by allow it.
Hikers "yogi" when they cajole a non-hiker out of something they need or want without actually asking for it. It's named after the Yogi Bear cartoon figure because of the way he made off with tourist picnic baskets.
Hiker yogi-ing is mooching food, a ride, or anything else of value from locals or from day hikers.
To yogi successfully one needs to look pathetic enough so people will want to help. Asking for a handout is considered begging and not real yogi-ing.
Yogi-ing may also include the "innocent" or "accidental" theft of another hiker's food, snacks, or rare treats, especially while on tight rations due to the thief's poor planning. Sometimes the logic used is "You just left it there", or "I didn't think you wanted it", or "I thought you were done with it". And so on.
But more purely yogi-ing is an art, the art of "letting" food be offered cheerfully by strangers without actually asking them directly. While asking for something is generally not allowed, and begging is not fair play, and actual stealing is out, limping, wistfully staring, or similar hints are allowed.
Ed is a master of yogi-ing. He hardly has to carry any supplies at all. But then yogi-ing is an art quickly mastered by the hungry, and Ed is always hungry.