Oh god though that question casts a huge net hahah. Like it depends a bit on if he’s got it from stuffing or vore (or a mix of both). BUT since he is complete and utter trash I think he could use his appetite to score some easy bucks placing bets in a bar on how much he can eat and drink, and when he’s already got a good sized belly and seems full he asks double or nothing and then keeps eating to get bigger. And then when he’s tipsy and possibly with someone he’ll wanna use his belly to get off because trash. Hahah I like the idea that he gets a belly before some mission or battle and has that to deal with during the action, just because I like the image of his belly sorta wobbling like in the header and him trying not to hurl when things get rough. Or y’know if Leo made some snarky comments about his gut, Zapp uses it to pick on him. Like trying to get through the door at the same time and has his belly squeezing the air outta Leo, or pretends to not see him there on the floor reading something and yawns before flopping stomach-down on his face, suffocating the poor guy all over again. .. y’know I think for this sake Zapp would continuously eat to keep his belly bloated out.