Get ye flask.
Drop ye flask on the floor, on its side.
Ye watch as ye flask be turning forever.
You can try this on the beginning chapters of the game. Just find a lab flask on any 'ol laboratory table. Not a beaker. A flask.
Second one is also in the beginning of the game. Know where the the exploding microwave is? Next to that you’ll see the guy who tells you to get out of there after exploding Magnusson’s food (YOU BETTER X LIKE A Y). Next to that is the broad at the table. She has a cup of coffee or hot chocolate. Swing that around and notice how the coffee inside doesn’t do anything. It’s solid. Turn it upside down. Nope. Still there.
Soda cans popping out of the soda machine are open. Gordon still drinks it. Gross.
I think it might be the first elevator in the beginning chapters of the game. Walk inside, hit the switch. Whoops, you fall off since there’s no railing. If you survive the fall, you can’t go through the doors. Reloading the game and staying in the elevator allows regular progression when you get to the bottom floor.