On HN you only indent two spaces to turn on monospace.

Here is the lisp with formatting:

  (defun my-org-screenshot ()
    "Take a screenshot into a time stamped unique-named file in the same directory as the org-buffer and insert a link to this file."
    (interactive)
    (setq screenshot_dir ".\\images\\")
    (setq tilde-buffer-filename
          (replace-regexp-in-string "/" "\\" (buffer-name) t t))
    (setq filename
          (concat
            (make-temp-name
              (concat screenshot_dir
                      tilde-buffer-filename ;; attempt to make irfanview approach work
                      "_"
                      (format-time-string "%Y%m%d_%H%M%S_")))
            ".png"))
    (insert (concat "[[file:" filename "]]"))
    (org-display-inline-images))