What do you mean it will hurt like hell? If you open your eustachian tubes, the pressure is equalized, so you don't feel any discomfort at all.
If you have problems in your ear, such as a perforated eardrum or an inflammation; you may still be able to equalise pressure, but it can be painful to do so.
Other genetic or congenital conditions exist that can prevent or hinder pressure equalisation.
Planes can't even get close to being perfectly rigid, because they'd be too heavy to get off the ground.