I've got a few, but I got really irked this past Saturday. So I caught up to a group of 4, they cleared out, teed off on the next hole but then waited for me to play through, much appreciated by me. A guy in the group chatted with me and told me I should play in the monthlies, I shook his hand and continued with my round, appreciating the group for being nice/letting me play through and advocating for the local league. Then, with four or five holes left, I caught up to a group of three who continued to throw even after seeing me (solo) waiting for them to clear off the hole. On the second to last hole, they say, "We'll be out of your hair in a minute" and I said cool, thinking it was their last hole (no one starts on the first hole, the road to the parking lot is closed in winter). I finish said hole and find they're playing the next hole (my last) and get really annoyed. So they finish and don't yell clear, the basket is uphill and to the right, can't see it from the tee pad. I play the hole and as I'm walking to the car, they're sitting on the bench of the next hole and talk to me about playing in the monthlies and I was polite and talked to them and finished by saying have a good round. Turns out it was their last hole and they were waiting for me to try and convince me to play in the monthlies while I waited for their group for 5 holes because they wouldn't let me play through. WHAT THE HELL! Sorry to rant, but it really peeved me that experienced players wouldn't let me play through for 5 holes and then waited for me to try and get me to play monthlies, really it was f'n rude.
Next day I accidentally threw onto a group because I assumed there was no one in front of me :doh: Turns out three dudes were just out of my line of sight, I apologized and they were awesome about it. I'll never forget to check blind holes now, that was an awful feeling when I saw that I threw on a group that I don't want to feel again, my heart rate jumped to like 150 when I realized it.