I think I have yet to meet a guy who has made me just bumble and completely lose my mind. Maybe one day.
I mean, I'll get nervous and blush easily and be awkward, but I do all that stuff anyway for other situations in life so it's not extremely new to me...
Oh, I can remember one instance when I was 18 and said the stupidest thing in front of my crush. I was so nervous. He was drinking out of a foam cup, and I said "Haha, I used to eat foam." I did, when I was a kid, a couple times I ate foam out of a chair we had. Strange, I know, but WHO says that?? WHY did I think it'd be a good idea to say that??