The dumbest thing you done in game....

[Xivia4]

Selling something really important by accident and then having to pay a 20% mark up just to get it back.

While on my way to whiterun for the first time, "hey, that giant isn't showing up as a red dot on my compass, I think I'll run up and try to talk to him..."

I know this post is from Dec 11 but when I first saw the gameplay demo from Todd Howard for E3 he specifically said that giants aren't hostile and even showed a clip of his character walking along side one of them with some mammoths in tow. Naturally, when I got my game and saw a giant with no red dot I too thought the same thing and went up to him only to be greeted with a club to the face.

Why yes, Nazir, I have been to the cloud district!

 

[Raijin]

I became arrogant enough that I thought I was immortal with my dragon shouts. I thought I would pick a fight with the greybeards... come to find out that they gave me a serious ass kicking. I would never try to fight with one again.

 

[The Fatalist]

My most memorable was summoning two storm antronachs against Morokei (A Dragon preist).
It went from a 3 on one battle in my favor to a 3 on one battle against me. PLUS the electricity damage kept sapping my magika, so I couldn't summon something else or retake command of my antronachs.

I've also thrown a cabbage at a Markarth guard with telekinesis. Got arrested.

I later killed nearly every guard in Markarth because I refused to go to prison for a crime I didn't commit. I just assumed that every guard that entered was also corrupt. I guess I could blame the mass pile of corpses in the Markarth temple of Talos on the Thalmor, even though I eventually gave in because I had to talk to the Jarl.

The first time I came across a Pressure plate. I thought I'd go all Indiana Jones on it and place an item on it to set it off then walk past. Turns out it was one of those spiked gates of doom.

In a cave, thinking: "Wow, I can't see anything through this weird smoke, I might light a tor..........." *Explosion*

Used the wabbajack on a rabbit while level 5. It turned into a Dremora an decapitated me instantly.

Also when I sell lots of random items in bulk, I find to my dismay that I have not actually been selling my junk; I have been buying my old junk off him that I sold on my last visit. Worst case scenario is that I lose all of my money.

 

[TheOtherTed]

I'm currently playing as a thief, and I picked up that "Light Foot" perk in the Sneak tree - the one that lets you walk on pressure plates without triggering them.

I'm doing the second part of that Ivarstead barrow quest. I see a pressure plate, and around the corner I see a solitary Draugr. I one-shot the Draugr with an arrow, I sneak over the pressure plate, a second later I hear a click, and BOOM! I get owned by a swinging log. Took me a second to remember I'd brought Iona with me.

But that's not the dumb part. The dumb part is when I made the exact same mistake with a plate-triggered swinging door trap minutes later in the same dungeon.

 

[multireaper97]

for me it was doing the dark brotherhood quest early and assasinting the king only to be chased all through solitude looking for a way out with 50 guards behind me
or my favorite was i saw a hagraven at level 3 thought it looked easy only for it to charge at me and rip me to shreds

 

[Hermaeus_Mora]

I made Sven a blade....

 

[Google]

I traded my thieves guild armor for gold...

 

[Hermaeus_Mora]

There's 3-4 more sets lying around the cistern

 

[butcherpete2277]

It was my first playthrew and I had just seen the loading screen that said giants were peaceful, so when I came across a giant outside whiterun fighting what looked to be bandits (the companions). I tried to help the giant, the giant died, and Farkas shoved a claymore through my stomach...

 

[Neriad13]

I reloaded a save because I'd misplaced my camping kit and wanted to get it back after I was sure that it had glitched through the floor. I reloaded, only to discover that I'd reached a save which was prior to the defeat of a mini vampire boss who'd I'd overpowered fairly easily with a few well-timed crossbow shots. No matter what I did, I couldn't replicate what I'd done previously, had to fight the vampire hand-to-hand for ten minutes, used up just about all my health potions and still barely came out of it alive. If only I'd paid closer attention and hadn't cared so much about the damn kit! T.T

 

[Epic Keith]

Murdering Nazeem and Ahlam and then running to their bodies, the moment they were killed with the murder weapon in hand