FULL OF PISS AND VINEGAR... To say that people are “full of piss and vinegar” is to say that they are brimming with energy. Although many speakers assume the phrase must have a negative connotation, this expression is more often used as a compliment, “vinegar” being an old slang term for enthusiastic energy.
Phrasefinder.org: 'Full of piss and vinegar'
Rowdy, boisterous, full of youthful energy.
The earliest citation I've found is from 1936 in John Steinbeck's
novel In Dubious Battle:
"Listen, mister," London said, "them guys is so full of piss and
vinegar they'll skin you if you show that slick suit outside."
Steinbeck was clearly pleased with the phrase (although it is unlikely that he coined it himself) and repeated the use of it 1938 in his better known novel The Grapes of Wrath:
Grampa walked up and slapped Tom on the chest, and his eyes grinned with affection and pride. "How are ya, Tommy?"
"O.K.," said Tom. "How ya keepin' yaself?"
"Full a piss an' vinegar," said Grampa.