One day in the early 1960s, John Lennon walked into London's Indica art gallery to visit an exhibition of avant garde art. Among the exhibits was a fresh apple. Inspired, Lennon impulsively plucked the item from its stand and took a bite. When the artist, who happened to be right there at the time, cried out in anger, Lennon sheepishly grinned and replaced the apple.
The artist in question? Yoko Ono.
[With fifteen miles of galleries, the Hermitage in Leningrad is the world's largest art museum.]