The interesting point here is that when the grammar property finds the word "take'', it accepts it and has to move verb_wordnum on by one to signal that a word has been parsed succesfully.

Object -> Dan "Dyslexic Dan"
  with name "dan" "dyslexic",
       grammar
       [;  if (verb_word == 'take') { verb_wordnum++; return 'drop'; }
           if (verb_word == 'drop') { verb_wordnum++; return 'take'; }
       ],
       orders
       [ i;
           Take: "~What,~ says Dan, ~ you want me to take ",
                     (the) noun, "?~";
           Drop: "~What,~ says Dan, ~ you want me to drop ",
                     (the) noun, "?~";
           Inv: "~That I can do,~ says Dan. ~I'm empty-handed.~";
           No: "~Right you be then.~";
           Yes: "~I'll be having to think about that.~";
           default: "~Don't know how,~ says Dan.";
       ],
       initial "Dyslexic Dan is here.",
  has  animate proper;