You know how they have signs saying not to store stuff in front of the emergency exits and fire equipment?

Don't use safety features as extra space or attachment points or anything. Don't use the fact that something was designed to hold more for safety to mean that you can use it for more than you're supposed to.

Example:

One time two of us were baking cookies. We didn't have quite enough molasses so we wanted to get as much as we could out of the bottle. Since the recipe called for hot water one of us put some of the water into the molasses bottle, covered the hole with a thumb, and shook it to get the last little bit out. It took us a long time to get the kitchen cleaned up.

What went wrong?

• When he put his thumb over the hole and shook, he heated the air inside the bottle and increased the pressure. But this was NOT a pipe bomb because the bottle was stronger than his thumb–so if the pressure got too great his thumb would just pop off.
• So his hand was a safety feature. A pressure release valve.
• But he was also using the same hand as a support for the bottle.
• When the pressure in the bottle shot up, it didn't make a pipe bomb, it made a bottle rocket. And since he didn't have his other hand under the bottle as a real support it shot across the room, shattered, and sent hot sticky water and broken glass all over.

The cookies were ruined. So sad.