Take the water example...
The biggest difference between water and electricity is that electricity need a "path"... A conductor... If you cut a water pipe you get zero resistance and water flows-out all over the place. If you cut a wire you get infinite resistance and no current flows.
If you rubbed yourself on carpet, electrons rub off the carpet molecules and get attached to you, making you negatively charged with a surplus of electrons.
Now, you are essentially a charged capacitor. You don't need a complete circuit because you don't have continuous current flow and the charge just needs to balance-out between you and whatever you touch. If you touch another person, and that other person isn't touching anything else half the charge will flow into the other person. If you touch a (grounded) doorknob, you are "balancing" the charge between you and the earth (which means you'll get completely discharged).
You can't get continuous current because you don't have a complete circuit. Unless... You continue to rub your feet, transferring more electrons to your body.
If you touch a metal doorknob electrons will jump from you to the doorknob, but there's no apparent circuit either between you and the doorknob...
When you get close to the doorknob, the air "breaks down" as an insulator. The air ionizes and the air becomes a conductor. Higher voltage can "jump" a bigger gap. It takes a several kilovolts to break-down the air in a spark-plug gap and it takes millions of volts to get lightening.
especially considering the doorknob itself terminates into the wood of the door.
Wood is a poor conductor but that means the wood door is a good-enough conductor. If the door was plastic (or maybe very-dry wood) nothing would happen... Only a small charge would be transferred to the doorknob and you'd never know.