>>122757238They did a tale where Superman said there was something Earthmen did that Kryptonians COULDN'T. Anatomically impossible.
They go through the entire story with everyone trying to guess what it is. At the end, it's "smoking".
Maybe it was done as a Public Service Announcement. (They used to run those before filling those spots with ads for fruit pies.)
Maybe it wasn't canon. I don't think Lois ever tried to force Clark to prove he could smoke.
