Another couple of items can come under this heading, since they were originally nicknamed after the humble lunchbox but are now known by the name.
One is the the English sprinter Linford Christie, who, thanks to his perceived endowment in the lycra shorts department, was referred to as having a well-packed lunchbox. This was shortened in the tabloid press so he was known simply as The Lunchbox.
The other item is the case for a series of Sparc architecture computers manufactured by Sun Microsystems between the late 80s to early 90s. Rather than being a traditional wide desktop case (Sun's version was called a Pizzabox) it was a narrow, squat case which could be mounted sideways as well as on its base.