If you built an arena big enough to hold all the people of the world and had the entire population of the earth fill the seats, Jimmy Fallon’s enthusiasm levels would grow so rapidly, he would literally explode. His body would be ripped to smithereens, that’s how amped he would get. Following in the footsteps of their cute Tonight Show duet, Jimmy Fallon stopped by Billy Joel’s monthly Madison Square Garden show on Thursday not just to do a little “Sherry” and give a little wave, but to demonstrate levels of commitment and excitement heretofore thought impossible by science. He and Billy do “The Lion Sleeps Tonight”! Jimmy does his Mick Jagger! There’s an outfit-change! Enthusiasm scientists are probably watching clips from the show with their mouths agape, their enthusiasm scales sparking and shorting out.