This is my favorite cursed finding: https://github.com/zevweiss/booze

FUSE-bindings for "filesystems in bash", eg:

https://github.com/zevweiss/booze/blob/master/cowsayfs.sh#L5...

    cs_read()
    {
      if ! [[ "$1" =~ ^/($cowpat)/[^/]+$ ]]; then
        booze_err=-$EINVAL
        return 1
      elif [ "$3" != 0 ]; then
        return 0
      fi

      local msg="${1#/*/}"
      local cow="${1#/}"
      cow="${cow%%/*}"
      cowsay -f "$cow" "$msg"
    }