I'm a feeder only, so this is how I would like to stuff someone else. This scenario I came up with may seem super random xD But it appeals to me, so...
Well, I love Mario Kart. The Wii one specifically. I've been fantasizing with playing it alongside a fat guy, with a few boxes of minidonuts laying around the room. We play through all the tracks and, when he wins a race, he eats one up by himself. If I win instead, I feed him one and open one of his shirt's buttons. I think I'm pretty good at the game, so he probably would have nothing covering his gut before he realizes!
This goes on until he can't take another bite. If he is such a beast that we finish off all tracks and still has room for more, he is free to go crazy with the food until he is fully satisfied, while I do whatever he wants me to.
This could work for mutual gainers too, just making it so whoever wins feeds the other. Or they could make it so that the winner gets feed, if it turns them on more! Either way it would be something I'd enjoy seeing.
9 months