Why is Gabrielle adventuring sans shirt? Could it be because she was wearing stolen (and unlaundered—in every sense of the word) gear while robbing a chest in the Vulkhel Guard bank, and got totally busted instead?
Busted and killed and all of her stolen property confiscated, including the stolen jack. Which was the only piece of chest armor or clothing she had in her possession.
Heh. She did get this cool achievement for it though:
pies & heavy armor 