plain Jane

plain Jane (plural plain Janes)

1. (informal) A young woman or girl of average or unremarkable appearance.
   • 1954 November, Kiplinger's Personal Finance, volume 8, number 11, page 46:

     Charm school instructors […] can do something even for the plainest of plain Janes.

2. (informal, attributive) Something basic and ordinary.
   • 1989, William S. Brophy, Marlin Firearms, page 320:

     Many of the early models had both a "plain Jane" model with open sights and a Deluxe (DL) version that had an aperture rear sight and a hooded target-type front sight-and, in some cases, sling swivels.

• Alibi Ike, Dapper Dan, doubting Thomas, Gentleman Jim, gloomy Gus, good-time Charlie, nervous Nellie, sad sack, Silent Sam, average Joe, regular Joe