In The Language Instinct, Steven Pinker wonders what we say ping-pong and pitter-patter rather than pong-ping and patter-pitter. Why see-saw and hee-haw and not saw-see and haw-hee? You could ask the same question about shilly-shally, ding-dong, clickety-clack, riff-raff, flim-flam, chit-chat, sing-song, spic and span and a number of other expressions.
Fortunately Pinker answers his own question, "The answer is that the vowels for which the tongue is high and in the front always come before the vowels for which the tongue is low and in the back."
Pinker goes further. We tend to place "words that connote me-here-now" in front of words that suggest someone else or somewhere else. Thus we say this and that, not that and this; now and then, not then and now; friend or foe, not foe or friend. He observes that Harvard students speak of the Harvard-Yale game, while Yale students call it the Yale-Harvard game.
I long ago noticed at wedding receptions that you can tell from the gift tag which side a wedding gift is from. At Bob and Sally's wedding, Bob's friends and family will write "Bob and Sally" on their gifts to the couple, while Sally's friends and family will write "Sally and Bob."
All this has made me wonder about partnerships. Do any rules apply in how the names are ordered? In law firms, I imagine the senior partner generally goes first. But what about comedy teams like Abbott and Costello, Burns and Allen, Rowen and Martin, and Martin and Lewis? In these instances, the straight man gets top billing, but what about Laurel and Hardy, Bob and Ray, Stiller and Meara, and Nichols and May?
And then there are those famous musical partnerships like Gilbert and Sullivan, Simon and Garfunkel, or Rodgers and Hammerstein. I think it sounds better to us when the shorter name is listed first, and in most show-business teams that seems to be the case. It's Bert and Ernie, after, all, not Ernie and Bert. Yet Rodgers and Hart sounded just as good to us as Rodgers and Hammerstein.