While filming "Take Me Out to The Ball Game" Gene Kelly's perfectionism and constant ribbing began to annoy Esther Williams. Director Busby Berkeley came up with an imaginative swimming number for the duo but Kelly didn't want it in the movie. He continually mocked Williams for making money from swimming films, seeing it as not too difficult a talent.
Things escalated while filming a love scene seated on a bench, mostly due to Kelly's insecurities at being an inch shorter. Between takes he kept asking Williams to slouch or sit lower so he would look taller than she. Finally Williams responded, "Why don't you just stick your foot under your ass and shut up?"
If you notice, Kelly took this advice, and during the scenes where they are seated together Kelly is sitting on his leg and foot.