An arraignment is a hearing where the defendant can plead guilty, no contest, or not guilty. You can plead guilty, but the real question is whether you should or not. It would be a mistake to plead guilty at this time, especially without the counsel of a drunk driving lawyer in Massachusetts, and there are multiple reasons for this.
If you plead guilty immediately, you lose any opportunity to fight the DUI/OUI charge.
If you plead guilty immediately, you also lose any opportunity for a plea deal, if that is what would be best in your unique circumstances. Admittedly, a plea deal means you would plead guilty, but the process can render a better outcome than an immediate plea of guilty. In some jurisdictions, you may be able to plead down to a lesser offense.
If it's your first drunk driving charge, it can be tempting to plead guilty right away so that you can get the case over faster and get on with your life. But if you do not fight to get the charge dismissed or to get yourself acquitted, it will be your first drunk driving charge. With the latter on your record, you want to keep in mind that subsequent DUI/OUI convictions will assuredly lead to harsher penalties.