Originally, the bit bucket was the container on teletype machines or IBM key punch machines into which chad from the paper tape punch or card punch was deposited; the formal name is "chad box" or (at IBM) "chip box".
The term was then generalized into any place where useless bits go including the trash can or rubbish bin. In Unix, Linux, and unix-like operating systems, this term is used to refer to /dev/null. In OpenVMS, this term refers to SYS$NULL:. On Univac 90/60 operating systems such as VS/9, it was referred to as "*DUMMY". On DOS and Windows, it is referred to as "NUL".
The bit bucket is also used in discussions of bit shift operations. When the width of a given binary number is fixed, one or more bits are lost when performing a simple shift. These bits are said to have "fallen off" or to have "fallen into the bit bucket".
Such a device is sometimes referred to as a "write once read never" or WORN device (named after the magneto-optical WORM devices used during the 80s), and was indeed implemented as such as an Easter egg in early versions of Atari BASIC.