It is required to play the crane game (north exit) and to solve the pentagon puzzle (south exit) to get the key to the car.
Viewing post in Pent's Wacky, Zany Road Trip to Adulthood comments
Thanks. I had thought a while back that the crane game might have been what I was missing - but for some reason every time I tried talking to the cow, he always just told me to let him know when I wanted to play, so I thought maybe I didn't have enough money.
I can't remember if I ever actually tried speaking to him twice in a row until just now when you reminded me of it.
I can tell I'm going to be facepalming a lot playing this if that's how I started lol