There a ways to personalize your Gmail experience, and one of those is picking personalized Gmail themes which make emailing funner. But if you're not sure what kind of theme you want to use from all the available Gmail theme choices, there's an option called "Random" which provides you a random theme based on your geographical location, and will change when in a different location.
Step 1: Log in to your Gmail account.
Step 2: Click Settings at the top right corner of your inbox.
Step 3: Click the Themes tab.
Step 4: Choose theme of your choice and you are done.