Which pedal should be reverse thread?

Mine is the non-drive side of the bike, which I think is wrong because as I think, it would on screw while riding.

When sitting on the bike, the right side is "right-hand tread" and the left side is "left-hand thread".

I think you're right, but then, what do I know?

The right is normal thread and left is reverse thread, that way when pedaling they don't back out.

That is correct. Think about it, would you want it to screw off while riding or screw on?

I never know when people say right and left side of the bike if their point of reference is from the front or while sitting on the bike. Thus, using drive and non-drive side is less confusing.

In any case, the pedal on the drive side of the bike has a normal tread. The non-drive side of the bike has a reverse thread.

The reason for the reverse thread is to keep the pedal from working loose while pedaling. If your pedal comes loose while pedaling, it will booger up the threads of the cranks.

Hope this helps.

Right is right, and left is wrong.

That's the way to remember it. By this, I mean that the pedal on the rights threads like a standard bolt or screw. The pedal on the left threads opposite a standard bolt or screw.