The most embarrassing thing I do on the course is pretend I actually know how to play golf.
Once, while playing a course for the first time, alone, I holed out on the wrong green. A quick glance at the course map (or even the sign next to the ball wash) and I would have known it was a 90°to the right par 4 (like a 200x150). Instead I saw a green about 400 out and just went right for it. After I holed out and picked up my ball I'm heading for my cart thinking "where's the cart path?", then I look up and see I'm on a par 5... at this point I'm confused as all heck and then it hits me... "DUH!" Too bad I only had myself to laugh at myself as I was playing alone and the course was dead cause I teed off at like 630am. The starter and I had a laugh about it on the turn though. I didn't feel so bad once he told me how many others have made that same mistake on that hole.