Be careful when trying to cancel out of npc dialog or hilarity may ensue!

I accidentally punched out the apartment maintenance guy while he was thanking me. I doubt he'll be doing me any more favors!

There are some annoying citizens that I wish I could just sock in the face without the police gunning for me. Oh, in Deus Ex too.

I have a problem with throwing my grenade when I want to holster my weapon... 
After completing the factory quest and the police come in, I hit them with a flashbang and they shot me full of holes. 

I've accidently thrown some objects at innocent people instead of setting them down. I also chucked a cardboard box at the first cop on the rooftop of the first level. Fastest. Game over. Ever.

One time, in real life, I was coming to stop at a light and accidentally hit the brakes, running over the people in the crosswalk.  Then my car swerved right and I ran over a few people on the sidewalk.  they died too.

I found myself clicking RB by mistake when I was trying to sprint only to throw grenades instead at innocent bystanders.

I pressed B by mistake to open my invatory after completing the quest for Meagan's mom , knocked her right out.

I intentionally took some annoying people down after doing their quest. Knocked out I man as my first play through was pacifist. Incidentally don't fully upgrade your battery for that as the recharges are few and far between.

I did this to the cop at the police station. I don't know if I was trying to skip or something since it was an option I already heard. Knocking out an officer in a police station doesn't go over too well.