The "Caddyshack" actor wasn't playing well at all at the famous Northern California tournament ... so when a fan offered him a mid-round shot of tequila -- he downed it, and the video is hilarious!!
You can see in the clip ... Murray was walking up the fairway at one of the holes when a woman leaned over the ropes with a plastic cup full of booze.
"Hey, Bill!" the woman screamed at him. "I got a shot of tequila for you! I know you'll like it!"
Murray walked straight up to her, took the cup, slammed the drink, threw the empty and kept on walking like nothing had happened!