Jokes, Funny lines, pre 1950s

Unfortunately, there will come a time, if not already beginning, when 
younger viewers won't understand some of the jokes in the episodes. 
Specifically, I refer to jokes that refer to people, or happenings, etc. 
that occurred before the 1950s.

Maybe, it would be fun to make a list of these on this thread.  I will 
try to add to it, too, but it may not be for a couple weeks.

LC