I doubt it is the
worst shot I've ever hit at a great course - there are a lot of rounds I've forgotten by now - but the one that sticks in my mind is my tee shot on the 7th at The Old Course, the year I played in the Dunhill Links Tournament.
The day before, downwind, I'd hit a terrific tee shot up between the bunkers and actually putted for my second shot.
The fateful day, when scores counted, I was quite out of my element being in the first group off the first tee. [I'm not used to playing with galleries!] I scraped it around the first six holes, and when I got to the seventh, with a strong wind quartering into us from the left, I got nervous about losing the ball in the whins. [My professional playing partner had just hit his tee shot OVER the whins, and was about to re-load when I reminded him it was probably in play over by the 11th tee, and indeed it was.]
So then I stepped up and double-crossed a dead pull across the left of the 7th, and all the way across the 12th fairway, very close to the boundary with the Eden course! Luckily there was no one coming up the fairway at that moment, but it took a while after I'd slunk over there to have a chance to hit my second, because of groups playing the 12th and 11th.
After that I recovered pretty quickly [turning downwind, I made birdie from two feet at the 8th], and played pretty well for the next day and a half, before Carnoustie ate my lunch the last day.
A month or so after the event, I received by UPS a large, framed aerial photo of St. Andrews, that traces out all of my shots on the day, as well as those of my partner. I guess one of the scorers had a GPS unit and was keeping track, unnoticed by us all. So it's hard to forget my tee shot at the 7th, because its path is memorialized on the wall in my office.