Freebird!
It's like you want to ask the guy who yelled it, 'What are you -- 45?' I hate those people, but not the song.
So - my age is showing. I thought I was really funny yelling "Freebird" every time I heard someone in the family room whomping away with Guitar Hero. And the favor was returned on the night when I grabbed the mic and sang a long, painful rendition of Do It Again. (the two minute video clip has blessedly disappeared)

My sister and I once made a list of absurd places to yell "Freebird." My number 1 entry - a Papal audience.