I'm running my own VPN with couple of my friends where we share the same static IP. If I'm visiting some particular websites and ads are generated based on my browsing behavior, is it possible that the second user from the same shared IP will be able to see same ads as me (generated according to my browsing behavior)?
Well, it depends, ads are mostly not based on IP but more on cookies and logged in accounts. As an example, if you are logged in to your Google account and you are visiting some website that provides ads from Google and at the same time, one from your friends is doing the same thing you two will see different ads (this relies on your browsing history (i.e. targeted ads)). But if you are somehow anonymous on these websites you are visiting and also your friend is the same you will be seeing ads related to your IP (Time of year, area, etc.).