Now we've hit on something that's in my extremely limited
wheelhouse. The Marx Brothers film in question is "Horse Feathers"
(1932), and Groucho, as college professor Quincey Adams Wagstaff, strums
the guitar while serenading the delightful Thelma Todd. If you knew
those secrets words, the duck will fly down and give you absolutely nothing.
     "Horse Feathers" is the film that contains Groucho's immortal line
to Zeppo, cast as his son: 'I married your mother because I wanted
children. Imagine my disappointment when you arrived."
    Groucho picks up the guitar in only two of the brothers' 13 films,
"Horse Feathers" and the film that directly preceded it, "Monkey
Business" (1931). I don't know about Twain, but Groucho took the guitar
very seriously. He taught himself to play by ear in vaudeville, then
took lessons with the great guitar teacher Bill Mathes and cultivated a
friendship with classical guitarist Andre Segovia. He kept to a rigorous
schedule of practicing two hours a day.
    For those wondering if I'm stringing them along, the preceding is
submitted largely because I always thought there was a strong comedic
kinship between Groucho Marx and Mark Twain.  There are the wit and
wisecracks. There is the preeminence in American humor. There is the
trademark cigar. There is the often-scathing view of the damned human race.
    Maybe Twain didn't have a guitar to pass along, but from Mark to
Marx there seems to be a passing of the cigar in American humor -- the
Marx Brothers forming their earliest vaudeville act in 1909, just as
Twain is preparing to depart the scene.
    And when Twain was preparing to leave on his round-the-world lecture
tour, he could have used another of my favorite Groucho lines: "I've
worked my way up from nothing to state of extreme poverty."