"Full of spit and vinegar" meaning

I was reading a book and couldn't understand the meaning of this:

After all, how many times had her father complained that she was full of more spit and vinegar than most boys?

I searched, but I could only find mixed opinions that it could be both offensive and non-offensive meanings.

The only trustful source I found was on Oxford dictionary as "agressive energy". Can anyone explain it better? I want to grasp the full meaning of it. Examples would be good too.

PS: I'm not a English native speaker

Solution 1:

Apparently this phrase has several origins and forms

Vinegar has been in the language as the name of the familiar liquid since the 12th century. During the 1920s vinegar was used to mean vitality and energy and that's the meaning in 'piss and vinegar' and 'pep and vinegar'. At that time many phrases indicating a general perkiness and vitality entered the language, often for no other reason than linguistic exuberance. It's most likely that the phrase originated around then, possibly as an adaptation of the existing 'vig and vigour', which means much the same.

Spit and vinegar seems like someone did not know that 'pep' could be substituted for 'piss'.