in the hardware section at your local big box, there is a 'door hasp'. One side screws to the door, the other the wall/door frame. The wall side closes over the door side, hiding the screws so that they can't be removed without removing the lock first. When closed, you install your padlock and voila!
To avoid @mailpup's caveat, install said hasp/lock combo on both sides of the door, so it can't be removed even if someone pulls the hinge pins. Keep a set of huge bolt cutters hidden under your bed, because you'll need them when you lose the key.
Or you could try hiding your 'scissors' in a ziploc bag or mason jar secreted in the toilet tank... Of course, that's the first place the cops will look for your 'scissors'!