I got curious and had to investigate. It turns out that a lug is a method of packing, such as a crate or carton.
Here's what I found on this site => http://www.todaymarket.com/tmp_refe.htm
(They've also got pictures.)
Usually refers to a container that is placepacked in two or three layers, depending on the crop.
Lugs can also be bulk-filled. They are made of wood, corrugated fiberboard, or a combination of both.
Standard dimensions are 16 1/8 x 13 1/4 inches with varying depths.
Ventilation slots provide airflow and drainage to accelerate cooling and maintain freshness. Locking pegs limit container movement to prevent product damage during transport.
Capable of holding 8, 12, and 16 oz cartons or loose product. Designed for picking and shipping produce.
Produce Lugs stack and nest with either a 180° turn or with a 90° turn."