Both make valid points, though I’m with Starlight.
 
Christmas lights are the pits…

It gets progressively worse when two or three bulbs are out. You will never know if you changed the correct one.

Clark Griswald knows this pain.

@laofuzi  
Actually, there’s a very good reason Christmas lights are traditionally designed in series instead of parallel. While it is absolutely infuriating when you get to play find the dim bulb, there are other, more dire things that can go wrong. If there’s a short somewhere or one of the sockets accidentally bridged, the circuit can be broken, and the offending problem losing power more easily, while if the line in parallel, the problem is still getting power and can be be far more dangerous. Over time, better manufacturing and materials have made light strings much more safe, making parallel designs more viable, especially now that LEDs, in-line fuses, and better transformers are more common.

If you’re using a series circuit for your Christmas lights, that would spell problems as even one defective bulb will deactivate the rest of the other bulbs. Instead, buy Christmas lights that rely on parallel circuits, where the rest of the bulbs will remaining shining, even if one light bulbs goes out!

Christmas Decor, the world’s first Strand-type game.

Spike makes a very valid point. Test them first. Then just say, “screw this,” and buy a new set.

It’s always one light… JUST ONE LIGHT that never works and it ruins the entire strand! ARGH! So relatable!

@Background Pony #EE55  
Acctually yes :P

Can you see the lights in daytime?

Relateable :)