Are shy guys uncomfortable around girls they like?

Woah, I might just be this guy you talking about, so lets just pretend by some inexplicable force of nature that I am: I really REALLY do like you, and yes I am shy but the fact that YOU (someone who Id think is way out of my league for me to even notice you in the first place) started this nonverbal flirting you speak of is the very reason I had enough courage to warm up to you in the first place. I can tell you, based on past experience, its highly unlikely I will do anything to take this to the next level - what generally pans out is that you'll give off signs that you've grown bored of this, as a result I will start panicking for the next step so as to maintain your interest, begin acting really nervous around you, pretty much geeking- out whenever I see you, these episodes will leave me with dreaded thoughts that there is no way that you will like me now after I've made such dork of myself around you which pretty much reinforces the next geek-out episode, so basically its a vicious cycle. Based on conditioning I will continue having these episodes even after I've gotten over you, so don't worry I'm not a stalker or anything, there's a good chance I've already moved on.
My advice to you is if you do like me back and you want something to happen, keep doing what you've been doing because you've been brilliant up until now. Maybe try showing a little more encouragement, try your utmost to hide any signs of boredom if we having a chat, a small chuckle when I try to be funny would help too, but then again you don't have to be false either. I guess do whatever you can to keep the conversation flowing which will help it move away from the shallow one liner chitchat so we can then explore deeper topics. The more I can hold a conversation with someone the more comfortable I begin to feel around them and who knows maybe that's the exact kind of support I need to take it to the next level this time round

With shy guys, their outward expressions can be something of a flood gate. At first, they are too timid to approach a girl, flirt openly with her, or otherwise put himself out there for fear of being rejected.

However, when a shy guy is received warmly by a particular girl (ie. she shows interest in him, keeps the conversation going when there's a lull, etc.) or he feels that she may have an interest in him... it can give him that boost of confidence to put himself out there and act a little crazy knowing that as awkward as he may seem (in your case, trying to be overly funny) he has a chance with you, and if he shows effort/interest in you one of you is bound to ask to other out eventually.

Well shy people usually can be very outgoing... they just lack confidence that people will want to interact with them (probably treated poorly in social situations when younger). So if they know someone well they open up, or if given permission to be outgoing they'll do it then as well (speeches, acting, etc).

Both things might be true, he likes you, and now that he knows you better it means he is comfortable enough to be outgoing.

OMG exact same situation that is happening with me! It is so frustrating.

If he is normally shy and quiet around most people then I would take it as a good sign that he's open around you. He's comfortable, trying to impress you, and outgoing around you and that's good s0o0o I think that he might like you.