I watched John totally break up on stage at Winfield once when he got to the 'heavy breathing' chorus and some sweet young thing in the front rows of the audience joined him in counterpoint:

"unhh"
"eeee"
"unhh"
"oooh" ....(hard to appreciate her timing and fervor here)

you'd think they had rehearsed it, except John had to stop and re-start the verse....*big grin*