Computer is a dumb machine, it does what it is told to do. But we humans are smart and try to add fun whereever possible. If you are a linux user just open your terminal and type these commands to get funny replies.
root@tushar:~# ^How did the sex change operation go?^
bash: :s^How did the sex change operation go?^ : substitution failed
root@tushar:~# %blow
bash: fg: %blow: no such job
root@tushar%:~# nice man woman
No manual entry for woman
root@tushar:~# make love
make: *** No rule to make target `love'. Stop.
$ [ whereis my brain?
sh: 2: [: missing ]
% man: why did you get a divorce?
man:: Too many arguments.
% !:say, what is saccharine?
Bad substitute.
root@tushar:~# world
bash: world: not found
Enjoy!
Source - Tecmint