Six + Seven = ?

The other day my son and I went out to eat some yummy chinese food. We sat down and started talking well, mainly I was only listening because my son had lots to say. He was telling me about his ball games (as if I didn't attend them) and his new friends from his team. Then he said "mom, Jordan said he is six and next he's turning seventeen..." I tried not to go into details and just told him that was not possible. He repeated and insisted about this issue. I was getting aggravated because he knew better and plus, I was trying to enjoy my meal. Finally I said "Walter come on! What comes after sex!?" (I got all jumbled between the words six and seven...) when the people from the table behind me turn around and say "a cigarette!!!" and start this perverted little giggle. So here I am sitting with a small boy awkwardly staring at me waiting for a straight answer, the nosey people still giggling in the background, me thinking about laughing but at the same time thinking about turning around and telling them how inappropriate that was... but I guess it was just their lucky day. I didn't do anything. My egg drop soup was too good to be interrupted.