Button popping or a shirt slowly riding up on a full tummy?
I'm gonna say button popping.
I just love how excessive it is, even theatrical. How much pressure have they let build up for *that* to happen, and how entranced by the taste must they be to not even notice how tight their clothes were getting?
You've got strong emotions linked to button popping: surprise, embarrassment, relief, excitement maybe, or even fear if the sound was loud. A shirt progressively riding up is slower and has slower emotions too. It's more tender maybe, but tenderness appeals to my heart, whereas strong emotions tend to put me in a kinkier state of mind.
In a more realistic scenario, button popping shows how the person has gone overboard, but also means that they now have more room to go even further.
In an unrealistic scenario, you can have some rapid growing of the belly that the clothes seem to contain for a few seconds, until the button pops and the person keeps expanding (oops, dipping into inflation a bit there haha)










