The 737 slide is manually connected by a girt bar to two points on the floor. Of course it will not disarm if the door is opened from the outside. However if armed, the person arming it should place the red band across the window. If you are opening a 737 door from the outside, check that band is not across the window, and if it is, don't try to open it..
The 757 and Airbus doors will throw you out if inadvertantly fired.. Happened to a mechanic at a British MRO a couple of years ago, he was lucky to survive.