It was a rough day to be a Golden State Warrior on Thursday ... while Klay Thompson and Steph Curry were bad on the golf course, Draymond Green showed he's got ZERO skills when it comes to chugging beer!

The comically awful showing from the NBA stars all went down during the eighth iteration of The Match at the Wynn Golf Club in Las Vegas ... when the Splash Brothers were trying to beat Patrick Mahomes and Travis Kelce in the annual charity golf event.

Thompson and Curry struggled mightily against the Kansas City Chiefs superstars ... losing the contest in just 10 holes.

But, perhaps the bigger story happened earlier in the evening ... when Kelce gave Green a booze-slugging contraption and 12 ounces of Coors Light.

The tight end tried his best to get Green to pour it out properly down his throat -- but check out the video ... Green was awful!!

The 33-year-old got more of it on his shirt than in his mouth -- and Kelce was cracking up over it all!!

To his credit, Green was a good sport about the snafu ... though he did try to blame Kelce's device for the mishap.

For Kelce's part, he showed he had absolutely no issues with the thing just a few minutes before Green's debacle ... slamming a Silver Bullet in less than four seconds.

The day -- despite the Warriors' worst efforts -- was still a good one nonetheless ... it showed Mahomes is truly good at everything, AND it raised a ton of cash for various charities.

Good work, guys!