These are all taken from here. A lot of these don't seem to work on newer shells, but they're still possible to laugh at.
% make fire Make: Don't know how to make fire. Stop. % why not? No match. % gotta light? No match. % !1984 1984: Event not found. # (on some systems) % How's my lovemaking? Unmatched '. % "How would you rate Bush's incompetence? Unmatched ". % [Where is Jimmy Hoffa? Missing ]. % [Where is my brain? Missing ]. % ^How did the sex change^ operation go? Modifier failed. % If I had a ( for every $ Congress spent, what would I have? Too many ('s. % man: why did you get a divorce? man:: Too many arguments. % %blow %blow: No such job. % \(- (-: Command not found. % sh $ PATH=pretending! /usr/ucb/which sense no sense in pretending! $ mkdir matter; cat >matter matter: cannot create % cd /tmp % touch this; chmod 000 this % ln -s /usr/bin/touch U % U this U: cannot touch this: no write permission % rm meese-ethics rm: meese-ethics nonexistent % ar m God ar: God does not exist % make love Make: Don't know how to make love. Stop. Supposedly on older Sun's make will also tell you Make: Don't know how to make love. How about war instead? % sleep with me bad character % ^What is saccharine? Bad substitute. % drink yellow_pages yellow_pages: Is a directory %touch me %chmod 000 me %touch me touch: cannot touch me: permission denied % ar x "my love life" ar: my love life does not exist % ar x "matey, the treasure" ar: matey, the treasure does not exist % talk Gorvachev@Kremlin talk: Kremlin: Can't figure out network address. % talk Comrade Khruchev [Your party is not logged on]