How to flash led without arduino or 555 ic

The thing I'm having trouble coping with at the moment is why everyone is freaking out at me for experimenting... It's a spare LED out of a bag of 10 that I got for 5$.

The other thing I'm having trouble with is why everyone is spazzing out about a current limiting resistor when there's no extra voltage to drop with said resistor.

Instead of being a bunch of condescending assholes, you could instead fill the gaps in my knowledge.

To the best of my knowledge, you only get runaway current on an LED when you apply a higher voltage than what the led is rated at.

If I'd been putting 5V on the LED, I would have put a 1.5ohm resistor in series to limit the current. (1.2V/800mA=1.5ohm).

I'm confused how applying a series resistor that will drop voltage needed to make the LED run will benefit me in any way.