There are some ways to do it but keep in mind that they are risky and you didn't specify how much USD worth of BTC/Altcoin are you going to buy?, the best and safest way of doing it would be to start a thread in "Currency Exchange" section of the forum and for a small fee exchange your Paypal USD for Bitcoin, but again only buy from fully trusted members that have the history of exchanging the more or less same amount of USD for others before, and at the end keep in mind even after doing all that you are still taking risk buying here and unless the amount of Bitcoin that you are about to buy is small it's better to just do KYC for one of the better trusted exchanges and trade like the others.