Heidi dropped the hand with the whiteboard down, and gave him an exasperated look. Either he was being purposefully thick to be obnoxious, or he wasn't the genius he puffed himself up to be. The fact that she knew it was the former didn't help.
Eyeing the needle, she rolled her eyes, then her sleeve, slapped the already white-board contaminated syringe out of his hand, and stuck out her arm. If it would keep him from sticking little old ladies, she'd sacrifice a bit of blood--but damned if it wasn't going to be a needle that was neater than he looked.
At least the street was more or less empty, so it didn't look like she was shooting heroin in broad daylight. She mouthed the words 'I know something you don't', and waited for the retributionary stab.