If you get into a horrible, nasty accident doing whatever it is you do, help the police and ambulance crews track down your loved ones.
On your phone, go to MemeGenerator.net. At the top, click on God Tier, Demigod Tier, and so forth until you find an image that matches your incredible sense of style:

Click on the image you’d like to caption, and at the top right, there’s a form where you can fill in your own witty gem. The two edit boxes correspond to the top and bottom of the image. Below the edit boxes, you should see several country flags for languages, plus a “Generate” link. If you don’t see this, click on the “Read More” link in the meme’s description on the left side – sometimes the site’s a little buggy when the meme has a long description.

Click Generate, and you’ll get a new page with your image on it. If you’re using an iPhone, hold your finger down on the image itself for a second or two, and a popup will ask if you want to save or copy the image. Click Save.
Go into your Photos app, then go into Albums, Camera Roll. The meme will be your most recent photo – click on it to view it.

Click the bottom left icon with the square and the arrow coming out of it (forward?) and click Use As Wallpaper. Zoom it out by pinching so that the whole image is displayed, but keep in mind that the slide-to-unlock bar will take up space across the bottom. Click Set, and then touch the power button on your phone to put it to sleep. Hit it again, and the end result is:

It’s not perfect, but it’s an easy way to generate an amusing lock screen without busting out the Photoshop – or even using your desktop computer.