Similar to this question, but I'm asking specifically about bare wires, with no socket. I don't want to flip a breaker switch, or blow a fuse.
How can I test for a current in the cable(s) without a dedicated meter?
Maybe use this.
It glows when current is present. That way you won't have to touch the wire.
However, as stated by everybody, be careful.
Theoretically, you could take a lightbulb (or nightlight, phone charger, etc.) and touch the wires to the bulb base or plug.
This would be EXTREMELY dangerous: you could die from the electrical shock. Even experienced electricians and crazy people don't do such a thing!
This is one reason there are breaker switches: so you can safely work on wiring, etc. without dying.
To answer your original question with a good and safe idea: Don't do it! Use the proper equipment.