Show random posts INSIDE a category

Hi,

Hope any of you can help me with this. It’s been frustrating.
Please note that I’m not trying to display a random post or posts inside a widget or page.

What I need is:
I have a button on a menu and once I click on it it will show me all the posts from a given category (mywebsite.com/category/cars – for example).

Right now, as a normal wordpress behaviour, it will show me all posts from that category, based on the date. What I want is WordPress to ignore the date of each post and just randomize the posts order everytime someone visits and/or refreshes that page.

Why do I need this? Well, I have this website where I will have some posts by different people and I don’t want the visitors to see the same post on top, because it would give this post way more exposure than the older ones.

I’m not 100% new to wordpress or php, but let’s say I’m not an expert on both, so if you can help me, try to make it really simple, please 🙂
If you know the code and you can just type it, even better. That would make my life so easy 😉

Thank you in advance!