I don't do drugs

So yesterday while passing by eachother and making small talk we started "joking" around. You know, those dry pretencious jokes that have absolutely no substance? then I gave my Oscar winning laugh. So fake. The he blurts "Have you ever done drugs?" No, oh Nnooooooooo, I wouldn't even have the slightest clue where to get them if I wanted some. "you know, that's very rare, most people have done drugs, I never tried it either!" I don't know why he brought up this subject again. Boss does it at the most random moments, constantly picking my history to see if I've tried anything. Is it even any of his business? Is it? And if I have, does he really think I'll tell my buddy Boss that I have? sheesh.