HP 2100 computers (Old - 1970's) Easter Egg - Easter Egg from 1973 on HP 2100

Could this be the "oldest" computer easter egg?

In Hewlette Packard DOS system for their 2100
(later called 1000 series) mini-computers,
entering the console command:
WHY?
would return a response of:
WHY NOT?

This DOS system really only looked at the first
2 characters of commands, and in this case the
programmer implemented this so that the WH
in the command table was also used as part of
the OS code, so it made it difficult to remove.

I discovered this back in 1973 while testing
a binary/ascii dump utility on the system disk
pack (single platter 5MB disk "pack").