If you need to present a fake proof in a form of the mobile phone screenshot with particular conversation, you can use free SMS Generator! Web-based utility from Classtools.
Using it is simple. You are presented with the mobile phone screen, where you can initiate dialog, using the related icons at the bottom. You can use these icons to create a chat, written by you, between two historical of fictional characters.
You have additional options to modify and save your work. You can drag and drop, edit and delete your entries by hovering over them.
You can save your work for future changes.
After saving, you will also be able to get a QR code or embed the chat into your blog or webpage.
As you are already on the page, take couple of minutes to explore other fun mini-services offered by Classtools: http://www.classtools.net/