I just heard this colloquial sentence:
Mon copain raffole de ma tarte. À chaque fois, il s’en remplit la panse à en faire craquer ses fonds de culotte !
The idea of "eating tarts to his heart's content" is expressed by the part "s’en remplit la panse", but I wonder exactly what meaning the subsequent phrase "à en faire craquer ses fonds de culotte" adds to the sentence?
Is it related somehow to a similar expression "user ses fonds de culotte" that is used almost always metaphorically?