Sometimes people are funniest when they don't mean to be

My wife and I were talking about Beatles songs earlier this weekend. I'm not sure why although, sadly, it was probably because of American Idol.
Anyway, I mentioned the song "Yesterday". Leah said "That was played at my parents' wedding".

I almost hurt myself laughing.

You do know the lyrics, right? It starts:

Yesterday,
All my troubles seemed so far away,
Now it looks as though they're here to stay,
Oh, I believe in yesterday.

Suddenly,
I'm not half the man I used to be,
There's a shadow hanging over me,
Oh, yesterday came suddenly

Once I caught my breath and told her what the lyrics were she puzzled it over for a few seconds before deciding that perhaps that wasn't the song after all. (Side note - she's thinking of the song "If" by Bread. I read it in the newspaper clippings from their wedding that I saw while we were in Mississippi earlier this month).

Even now I don't think she's given much thought to why I find this so funny.