Webster’s Revised Unabridged Dictionary · 1913
Jag
Jag, n. 1. A leather bag or wallet; pl., saddlebags. [Scot.]
2. Enough liquor to make a man noticeably drunk; a small "load;" a time or case of drunkeness; — esp. in phr. To have a jag on, to be drunk. [Slang, U. S. & Dial. Eng.]