Wow. Now there's a question. I think the obvious answers are going to be anthemic songs like "Hey, Jude" and "All You Need Is Love", but I think in terms of catchiness, it'd be something like "We Can Work It Out" or "Across the Universe" or "She Came In Through The Bathroom Window".

How on earth can I pick just one?. I am The Walrus, She Said She Said, Here Comes The Sun, Drive My Car. I could go on and on(not a song of theirs, just a statement).

I am the walrus coo coo cachoo

Sgt. peppers lonely hearts club band.

OB-la-di OB-la-da

Now I'll be singing it in my head all day! :p

Eleanor Rigby. Musical masterpiece

yellow submarine

I wanna hold your hand