How to scratch an iPhone Screen?

I need my iPhone 5S screen to be scratched but I don't know how. I tried using my nails but nothing happened. I really need it scratched to maintain my chellengar teer.

I have tried looking at google but he is an idiot and is only giving me webistes about fixing a scratched screen.

I really need helps and I appreciate it.

Added (1). @ luke. I don't think I can invest that much money. Is there a cheaper option I can use? And also, its against my sommenars code to scream Obama

Dremel it, that will scratch it for you, or use sand paper.

Ok your gonna need to get really invested in this. Set aside about 8 hours of your day to do this.
You will need:

2 lbs of raw chicken
13 blue pencil crayons
2 rolls of duct tape
15 Nails
5 8' pieces of lumber
2 gallons of gas
Lighter

First use the lumber and 14 of the nails to build a table (Extremely important) then use the pencil crayons to poke holes into the chicken and pour the gas into the holes (Make sure to use All of the gas) then use the pencil crayons and duct tape to keep the chicken above the table. Then light then chicken on fire and scream OBAMA for the next 6 hours. Then when your done take the final nail and scratch it across your screen. (remember to repeat this process every 534 hours or the scratch will disappear)

Get a bobby pin, remove the small little circles at the end of the bobby pin, after you remove them, the ends will be pretty sharp, and scratch the screen.
Or use scissors, a nail, a knife.

A nail or a screw would do the trick

Use a butter knife and gently saw through it. Don't put too much pressure on it or it might crack and cause severe damage. Hope it helps.