Is being clumsy/doing stupid things a symptom of ADHD?

TL;DR People have no respect for me because I keep doing embarrassing little things that I have no control over. Could this be because of ADHD?

I have a tendency to do really stupid embarrassing little things uncontrollably and people's constant negative reactions towards me in response are driving me insane.
I was riding with someone back home from college, and after making a stop I made my way back to the car and went to open the backseat car door but it was locked. The guy I was riding with gave me the key and I tried to fit the key in the lock but it wouldn't fit. I struggled with it for at least 20 to 30 seconds before the guy I was riding with told me to unlock the front car door instead and to just reach in and unlock the back car door from the inside. I felt extremely stupid because I had sat there trying to mess with the key and I didn't even think of that.

Another embarrassing moment happened on that same car ride where I went to pump gas and I kept trying to fit the gas nozzle into the car but it wouldn't fit. I kept struggling with it for at least 30 seconds before I realized that the green gas nozzle was for diesel. I picked up the black, nondiesal gas nozzle and it fit into the car perfectly. I felt like a complete dumbass again. I could tell the guy I was riding with was amused but he didn't openly mock me.

Without going into too much detail the guy I was riding with is in two of my Computer Science classes so I see him fairly regularly at school. From that car ride onward I can tell he has no respect for me and talks down to me condescendingly and I can guarantee it's because of these awkward stupid things that I keep doing. I seriously wonder if some kind of mental disorder is causing me to do this, and from what I've seen on the internet, Inattentive ADD seems to be the most likely.
Can anyone else confirm that these instances of stupidity are a symptom of ADHD? It's extremely frustrating when everyone around you constantly mocks you for stupidity that you have no control over.

I wouldn't call it stupidity.
It's possible that the guy made you uncomfortable, stressed, or anxious for some reason which led to your lack of attention in these situations.
How are you with similar tasks on your own? And what type do you usually struggle with?

I do have pretty bad social anxiety so that could have been part of the issue. On my own I don't really seem to have these problems. It's like I turn into a different person, like Steve Urkell every time I'm out in public but when I'm by myself I feel like I actually am myself.

I wouldn't call that stupidity and i can totally relate. I have so many of those instances where its like "duh". I think for me, it's just part of the lack of attention to detail and trouble redirecting attention that comes with ADHD. But as the above poster mentioned, and as you said yourself, it could be social anxiety as well that makes it hard to think straight.

Yeah, it's for sure an ADHD symptom. Don't let neurotypicals tell you otherwise. They will just tell you redundant plateaus.