How do I stop a squeaky door without WD-40?

The squeak comes from metal rubbing dry inside the hinge. The quickest fix uses whatever’s already in the house: lift the door slightly to nudge the hinge pin up, coat the exposed pin with bar soap, petroleum jelly, or a little cooking oil, then open and close the door several times to spread it.

For a longer-lasting result, tap each hinge pin all the way out, wipe off the old grime with a cloth, add your lubricant, and slide it back in. Doing this to every hinge on the door prevents the squeak returning from the one you skipped.

Cooking oil works in a pinch but can gum up over months, so if you used it, revisit the hinge later with a proper lubricant.