So, I met this guy.
Truly inspirational first line, I know. So original I just might patent it and sell it, but it's gets better. So this guy and me sit next to each other in science, and I'm getting subtle signs that he's into me. He leans in close to me when we do group work, jokes, smiles a lot at me, asks me how I'm doing, blah blah blah. You know the drill. I like him and he seems to like me. I just, erm, have this thing where I melt into a pile of sad, sad awkwardness when a guy shows any amount of interest in me. As in I act like I'm totally uninterested, cannot even look them in the eye at all, want-to-crawl-under-the-desk-and-die sort of awkwardness. I have never really had a relationship because of this. For example, a guy will say something like "Hey, nice hair cut! It looks so great on you." And my brain somehow thinks the appropriate response is "Yes. It is shorter now, because of the... cutting of it like you said... how long before lunch?" It's awful. Is there anyway to stop my nerves killing this relationship before it even gets off the ground? Cause this guy seems really nice and I don't want to scare him away.
Hey, Sparkler. I'm sure you will be completely astonished to learn that I do this sort of thing too! It manifests differently for me, though—my tendency is for my mind to race in a million different directions at once, leaving my mouth to say absolutely nothing, or something extremely generic and noncommittal. I do manage to express that I'm interested, but then my mind goes "say this thing no wait say this other thing no urrrghbl" and I just sort of stand around like a boring dude who is bad. The root of the problem in both our cases is pretty much the same, though, and I have some advice that may help.
Method 1: Curiosity killed the... part of you that is stupid,
I have previously mentioned this as a thing that helps with awkwardness, but it is actually scientifically proven, so it bears repeating.
When you're suffering from Acute Onset Idiot Mouth, what's happening is that you're so fixated on doing something right (in this case, talking) that your brain overthinks how to do it. This is more obvious in my particular strain of Idiot Mouth, because I'm so frantically thinking of Right Things To Say that I either say nothing or respond in a way that no natural Earth human person ever would. So the idea here is to smack your brain on the nose with a rolled-up newspaper and go NO. BAD. until it ceases to overthink things. One way to do that is to be genuinely curious about the other person.
The way the authors of that linked study explain it, curiosity and anxiety are both common responses to social interaction, but they're opposed to each other. Anxiety is a feeling of being powerless, or lacking control ("What if I say a dumb thing to this boy and then walk into a telephone pole and the boy calls me a fat nerd??") while curiosity is exerting control ("I will command this boy to tell me things, and learn them with my brain, thereby understanding his innermost boy secrets!"). But in more practical, non-psychologist terms, this works because you won't flip the eff out fixating on you if you're busy fixating on him. Asking him things about his life or hobbies or whatever and genuinely wanting to know the answers helps you worry less about yourself (steer clear of anything super serious or political, though).
That's one approach to try, but everyone is different, so here's one that works the opposite way: recruiting your brain even more, instead of telling it to go jump in a lake.
Method 2: "Stress is fun! Life is exciting!! EVERYTHING IS SO COOL THAT I AM HAVING A BRAIN ATTACK."
Associating stress with positive outcomes, instead of thinking of it as a bad thing, can turn it into an influence that's actively helpful. One study supporting this idea monitored two groups of students who were taking graduate school exams—one group was coached in advance to associate stress with awesomeness and excitement and so forth, while the other group wasn't. The coached group performed substantially better, both on practice tests and on the real exams months later. In your case, you'd want to think "My heart rate is up, my mouth is going crazy, THIS IS EXCITING, aw yiss." Try to enjoy the nervousness—after all, lots of people jump out of planes or explore haunted abandoned ghost factories specifically to feel this kind of thing. I suppose I've always done this sort of thing with job interviews; I listen to music that makes me feel like a boss beforehand, so I walk in thinking "AARGH, I COULD WIN FIGHTS" instead of "wahh, boo hoo, I am awful." I can't give you a lot of specifics on how to implement this, because it's a very individual thing, but just try your best to think about how you're completely going to own this dude, in the face, romantically.
I hope one of these helps you out; if I were you, I'd try the curiosity thing first, because it has the added benefit of establishing that you're actually interested in the guy. The second method works well too, but it is perhaps too powerful—you may very well psych yourself up, only to kick open the door, scream "DATIIIINNG," punch the guy in the head and then make out with his unconscious face. You probably won't say anything stupid while doing it, though.