pi@rpi / $ sudo mount -o fmask=666,dmask=666 /dev/sda1 /pendrive/

pi@rpi / $ ls -ahld /pendrive/
d--x--x--x 2 root root 8.0K Jan  1  1970 /pendrive/

pi@rpi / $ touch /pendrive/test
touch: cannot touch `/pendrive/test': Permission denied

pi@rpi / $ sudo umount /dev/sda1

pi@rpi / $ sudo mount -o fmask=0000,dmask=0000 /dev/sda1 /pendrive/

pi@rpi / $ ls -ahld /pendrive/
drwxrwxrwx 2 root root 8.0K Feb 22 22:25 /pendrive/

pi@rpi / $ touch /pendrive/test
działa :)