Taylor Swift's

Body Is a Wonderland

5/23/2009 12:30 PM PDT BY TMZ STAFF
Last night at The Staples Center in Los Angeles, John Mayer showed up in the middle of Taylor Swift's concert to sing "Your Body Is a Wonderland" with the hot country star.



And, no, there's nothing weird about John serenading Taylor. She's 19.

The thousands of screaming tween girls, on the other hand ...