Not a standard question unless there's some indicator - i.e. impairment or odor.
You can't fake HGN.
We don't typically give a preliminary breath test roadside. The 'official' breath test machine requires an operator to take a three day course to become certified, plus routine testing/calibration/etc to ensure accuracy of the equipment. Roadside PBT's don't undergo the same scrutiny and won't hold up in court.
Based on the facts and circumstances present, would a reasonable person believe that you were under the influence of alcohol or a controlled substance while in control of a motor vehicle? If yes, there's probable cause for a DUI arrest. I would request a blood test and if you refused, your license or operating privilege would be automatically suspended by the State of NH. You could appeal (and possibly win) the hearing, but after you pay towing fees, legal fees, and the citation you're sure to get from the original offense, you'll wish you weren't a dumbass.
However, I can't tell you first hand - I have yet to run into someone that stupid.
/thread