I think Pickle scared me the most as he would hide quietly if out of the cage and I could never find him to put him back! The biggest scare was when I actually forgot to put him back in the cage one night! He was more of a sofa hamster and quite docile so I could easily pop in and out of the kitchen with him on the sofa with a hide and a tunnel and he wouldn’t try and jump off and one might I went in the kitchen then just went to bed! Completely forgetting he was still on the sofa. Next morning I remembered. Of course he wasn’t still on the sofa. We turned the room upside down looking for him - searched every room in the house and no sign of him.
That night I put his cage on the floor with a tube leading up to it and a trail of food, and set the night cam on the cage. Sure enough, not long after the lights were out he emerged from under the sofa and walked back into the cage. At which point I nipped downstairs and closed the cage door before he came out again. Now we had moved everything but he clearly kept changing his hiding place!
Of course after that he has no qualms about climbing off the sofa and free roamed after that but it used to take ages to find him to put him back in the cage!