I wonder if Howard
used a RADIOACTIVE tracer.
The Big Bang Theory Season 4, Episode 18
like a RADIOACTIVE monster!
The Big Bang Theory Season 7, Episode 20
I may be
slightly RADIOACTIVE.
The Big Bang Theory Season 11, Episode 17
That stuff's RADIOACTIVE.
The Big Bang Theory Season 6, Episode 8
...so, you know,
I could separate RADIOACTIVE isotopes.
The Big Bang Theory Season 1, Episode 16