Sex on washer machine. You don't need to wait several days for small deposits to verify your bank account. Sign in. No, we don't have admin fees. Internal Tooth Lock A washer with internal 'teeth' Used to prevent nuts and bolts from backing out. Hex Washer A hex head with built in washer. Smarter Living. More From Best Life. In the industrialized world, these designs have been superseded by the electric iron, which uses resistive heating from an electric current.