You put a big phone in a pocket not big enough resulting in excessive pressure. Who would have thought enough pressure could break a phone?
SHOCKER: In related news the new iPhone will break when used as a hammer or when subjected to explosives.
Don't you think Apple should make their phones strong enough to withstand normal usage & environments - rather than users having to change their clothes or behaviour to suit Apple's increasingly fragile designs? Particularly given how much Apple boast about their design skills and materials research.