Wearing a waffle pattern shirt can also make the reading high. My blood pressure is 20 points higher if I wear a waffle pattern shirt than if I take it off.
That sounds like the guy who thought he had a leather allergy because whenever he woke up with his shoes still on he had a terrible headache and felt nauseous.
It only happens with waffle pattern shirts and changing shirts causes a consistent decrease in blood pressure measurements. My doctor pointed it out when I got a physical because he'd seen the same thing before with other people.