Whee! Time for another food fight!
Try
SNOBOL for laughs, it will make you think Perl RegExes are fun light reading.
{long pause}
Okay, next idea. FORTH is the genesis for the
OpenBOOT initiative which underlies some recent system boot processes including Sun & FreeBSD. Imagine a coding system which can give you a complete interactive console-based IDE in 2K bytes booting your entire modern PC!
The suggestion has been made many times, but I'll echo it. Learn C and make and study the source code of FreeBSD or Linux... so much to learn!!!