Mary Cooper:  Well , I would have to say when he was _ thirteen _ and he tried to build a nuclear reaction in the tool shed .
Sheldon Cooper: Ooh , this is a good one .
Mary Cooper: Now , the first thing you need to know about Shelly is , ever since he was a little boy , he was always concerned with the well - being of others . And he did n't think it was fair for people to pay for electricity , so he was gon na power the entire town for free .
Sheldon Cooper: Tell her about the uranium ! Tell her about the uranium !
Mary Cooper: Oh , well . Well , this is adorable . When he arranged to get some yellow - cake from Chad , I thought he was talking about twinkies from one of his friends .
Sheldon Cooper: Yeah . But I was n't , because I did n't have any friends .
Mary Cooper: No . It turns out this little scallywag was trying to use my Visa card to buy uranium from an African warlord in the country of Chad .