I'll start. I've only just started my 2nd playthrough and went to Sloan the town up north from Goodsprings, thought I'd drop in and see if there was any loot there.
There was ammo on the table and didn't think they would mind if I just took it thinking worse case they'll just take it back. I was wrong the whole town turned hostile so I ran towards the quarry. I turned around and had like 8 people shooting at me. Luckily I have my vault 13 armoured suit with decent DT. Bare in mind I was level 3 at the time.
I turned around and to my horror I see a deathclaw running towards me and not a young one either. So i turn around again and now I'm running towards them lol. They start shooting at it and I manage to run far enough away out of trouble and get my binocolaurs out thinking they might kill this deathclaw as there was 8 of them.

Again I was wrong and by this time it had made it to town too and killed poor snuffles . Poor guy only just had its leg cured.

So yeah that was a straight re-load for me, all for a box of 10 mm ammo.

What kind of clumsy moment have you had?

I spazzed out and shot a mini nuke at an enemy (can't remember what it was) from 2 feet away while it was getting swarmed from people on my team... I will safely assume they were not happry with me after that.

I recently had a Dead-is-dead character die when I discovered the gravitational pull of the Lucky 38 Penthouse relative to plasma grenades is over 9000.

Accidentally made someone mad in Gomorrah and the whole place was after me.

I couldn't even get out of the building because I would die before getting to the exit so I had to reload a save that was an hour before.

^This: Black Mountian

Nothing spectacular for me, but the first time I did the quest with the fake ambush, I took it at face value. Forgetting that I was only supposed to observe, I took out my Plasma Defender and opened fire on my "attackers". The guide escorting me, secretly in league with them, wasn't too happy I'd begun liquefying his friends. I found myself in an "accidental" crossfire. Then, as the last ambusher fell, was killed by a bullet to the back of the head from my supposed ally.

Took me about a dozen attempts to clear the Deathclaws out of the quarry. Memorable moments include: sneaking up and laying C-4 charges only to run backwards, frantically trying to detonate them, when I was spotted; sniping Deathclaws and thinking everything was clear only to have one sneak up on me; completely missing Deathclaws with the one shot left of my most powerful weapons and then running away; and lots more running away.

I swear by the 6th or 7th attempt Raul was giving me a strange look and the whole town of Quarry Junction was laughing at me.