...to buy URANIUM from an African warlord...
The Big Bang Theory Season 8, Episode 23
because Santa wouldn't bring him
enriched URANIUM.
The Big Bang Theory Season 7, Episode 10
Tell her about the URANIUM!
The Big Bang Theory Season 8, Episode 23
...and then try to buy URANIUM...
The Big Bang Theory Season 4, Episode 18
...and told him it's against the law
to have yellow cake URANIUM in a shed.
The Big Bang Theory Season 1, Episode 4