If the muscles are relaxed, the sack shrinks, and all you see is a little white point.

当肌肉放松，色袋就会缩小，你就只能看到一个小白点。

youdao

He should wear twinkling patent leather boots and in the breast pocket of his sack coat there should be a white handkerchief protruding about three quarters of an inch above the vent.

他该穿双闪闪发光的漆皮靴，短便衣口袋上应该别一条白手帕，露出来四分之三英寸。

youdao

There were loud cheers as President Museveni held the white sack containing 250 million shillings aloft, before he handed it to a representative of the Busoga Youth Forum.

BBC: President Yoweri Museveni holding a bag of money