I leave my office door cracked as an ingress/egress point for the cats. Often, I feel the cold air from the other room seeping and turn to find it wide open - I'm awfully curious how it gets that way because I've watched Marko on several occasions narrow and ooze his head and body through like Senator Kelly escaping his cell in X-Men after he transmuted into a mutant; the door remains ajar at the same angle.
The answer was discovered this morning when the enormous Momo burst through the crack like the Kool-Aid man (OH YEAH!) swinging the door wide. Given her size, apparently subtlety is not in the realm of her capacity.