Is it normal that guys scare me?

I do like guys, but when it comes to talking to them or interacting with them I just switch off. Im not the most outgoing person but I now how to laugh with the girls. Its just when they start talking to their guy friends I sort of go all quiet and painfully insecure. Its almost like if I dont talk they wont look at me and so they cant see all the stuff I hate about myself. Does anyone else have this problem or any tips to get me out of my shell?