How do you act around a guy you like when your nervous? Girls please? Many answers :D?

Do you get a little flustered? Do you try not to show it at all? Does your heart start racing? Do you completely try not to show anything? If he looks you in the eyes, do you feel more nervous? Do you get itchy and hot? Do you feel warmer? Feel your pulse? Do you do your best to bluff it and make sure he doesn't figure out? What happens when you do that and he takes it wrong? How do you feel? Please help me and enlighten me because I'm a clueless guy? :)?