I still get shy around guys.
Its laugh cuz its ridiculous. I have a lot of male friends, and am actually pretty flirtatious. But it usually happens when I'm around a guy I have a crush on, I just get all tongue-tied and I can never think of anything cute/witty to say.
Even with guys who I used to be cool with, let me start having feelings for them, and then I start acting so weird.
But I'll say this. If you have issues with shyness, play it up and make it cute or intriguing. Work with what you got. If you have nice eyes, you can kind of "talk" with them, and he'll think you're mysterious. Smile, but not TOO too much though. A little aloofness is good if you play it right. I think this works well if you're in a group convo and you have a chatterbox girlfriend who loves attention and is dominating the conversation(I speak from experience lol). If there's a dude you're sorta feeling in the group, lock eyes with him for a bit, kinda smile almost like the two of you have an inside joke, and look away. Do this a couple times, and 9/10 I bet you he comes over and asks you what you're thinking.
I have a friend who is HELLA introverted but she is ALWAYS pulling guys. I picked up tips from her.
Or if its just you and him and you can't think of anything to say, just be cute lol. Smile a lot, laugh at his jokes, be ULTRA-feminine with your mannerisms, speak softly, etc. From what I've seen, most guys think its cute. As long as you respond to his questions, etc in a fairly articulate manner, you should be fine. I've seen it work on my male friends.
If you're shy, you may never be a big talker so your body language is important. Eye contact is your best friend if you're not great with verbal communication. Practice in the mirror with looking up through your eyelashes, side glances, shy smiles, flirty smiles, sexy smiles and feminine mannerisms. The more alpha male-ish he is, probably the more intrigued he is by femininity.
I'm a huge introvert (INFP) so shyness is something that I've dealt with my whole life. But it doesn't have to be a problem. I practiced most of this stuff on my platonic male friends that I wasn't attracted to and over time I've gotten much better.