no sweat（interj.）
"no problem, that can be done without difficulty," U.S. colloquial, attested by 1953; see no + sweat (n.). Said to be originally military jargon from the Korean War.
The universal and all-inclusive word today is "sweat." It covers just about everything: "no sweat" means no trouble, no cause for worry, nothing fouled up, don't fret. "It's a sweat" means a patrol looks tough, or an order to dig some more trench is an outrage, or simply that everything is messed up as usual. ["A Frontline Picture No Camera Could Get," Life magazine, March 16, 1953]
该词起源时间：1953年