HBO Watch Party is a browser extension that allows you to watch HBO Max remotely with friends. It synchronizes video playback and adds group chat to your favorite HBO Max content. To use HBO Watch Party, you will need to have a HBO Max subscription and the HBO Watch Party extension installed on your browser. Once you have the extension installed, open HBO Max and select the content that you want to watch. Then, click on the "HBO Watch Party" button in the top right corner of the screen. You can then invite your friends to the watch party by sharing the link with them.