Two's company, a troika is a crowd.

x-bonus Quote from Josh Billings. Another forgotten newspaper great, like Peter Finley Dunn.
Here's another of his:When I was a boy of fourteen, my father was so ignorant I could hardly stand to have the old man around. But when I got to be twenty-one, I was astonished at how much the old man had learned in seven years.

I remember seeing this attributed to Mark Twain.

Later I found it attributed to Josh Billings.