I get pop ups saying I have viruses on my iPad

SCAM! Do not click on any links. Do not call any phone numbers.

Clear your iPad Safari cache

Settings -> Safari -> Clear History and Website Data

This can happen when surfing to a web site where a malicious Ad leave Javascript in your browser cache to generate these pop-up.

No web browser on any platform can see outside of the browse to find anything good or bad with your device, so all they are trying to do it get you to give them money or gain access to your system in such a way that they can steal information from you that can lead them to stealing your money.

If you did contact them in anyway, change any account passwords you may have given them, if you gave them a credit card contact your credit card company and get your card number changed.

The messages are a scam. iPhones don't get viruses, unless jailbroken.

Go to Settings > Safari > Clear History and Website Data.