I had a boy over last night, somewhat unexpectedly. After he'd gone I went into the bathroom (which he'd used), and...
there were used (capped! I'm not a total slob) syringes lying on the countertop and a home blood pressure monitor on the floor.
He never actually said anything about them, of course. He didn't do anything to make me think he had noticed them - but they were right there. Of course he noticed them.
There's nothing like a "hi, welcome to my home hospital" to pique a man's interest.