Extreme 2-in-1 Socks by Kory Stamper

Extreme 2-in-1 Socks

Knitting
Fingering (14 wpi) ?
Double-Knit Stockinette
350 - 450 yards (320 - 411 m)
Large
English
This pattern is available for free.

The article for this pattern in Knitty is written such that it can be adapted to any gauge.  This is not so much a pattern as it is a tutorial for the technique of double knitting 2 socks at the same time, so adapt it at will.

ETA: There are a number of variations on the technique (including instructions for a flap-and-gusset heel and toe-up socks) at harmlessdrudge.com.