The Jargon File (version 4.4.7, 29 Dec 2003):

Godzillagram
 /god?zil'@?gram/, n.

    [from Japan's national hero]

    1. A network packet that in theory is a broadcast to every machine in the
    universe. The typical case is an IP datagram whose destination IP address
    is [255.255.255.255]. Fortunately, few gateways are foolish enough to
    attempt to implement this case!

    2. A network packet of maximum size. An IP Godzillagram has 65,535 octets.
    Compare super source quench, Christmas tree packet, martian.


The Free On-line Dictionary of Computing (30 December 2018):

Godzillagram

    /god-zil'*-gram/ (From Japan's national hero and
   datagram) 1. A network packet that in theory is a
   broadcast to every machine in the universe.  The typical
   case is an IP datagram whose destination IP address is
   [255.255.255.255].  Fortunately, few gateways are foolish
   enough to attempt to implement this case!

   2. A network packet of maximum size.  An IP Godzillagram has
   65,536 octets.  Compare super source quench.

   (2003-10-07)