I think this one is the amazing trick for anyone, because it sounds very less possibilities, But it is possible in a very easy way.
Firstly, you need to do is, go to the MicroSD card and then click on the Whatsapp and later on on the Database option.
After you are done with the first step you will find two files namely,
After finding these two files, you just need to do is take these files from your friends mobile and then you will be easily able to read their conversations that they have done with their friends. You can open them using a simple text editor.