When a guy tries to look at you then ignores eye contact like he doesn't care?

I've had two guys do this to me yesterday then completely ignore eye contact. What does it mean? Is it because they caught the girl looking at them and is embarrassed or doesn't care about them but had thought the girl was pretty but isn't. My crush even gave me long eye contact but I was too shy to look up him.......... ????????

It means they have a crush on you. I know its how I behave with a girl I like. The guy will look towards there direction but they dont want the girl to think the guy is a creep so when the girl looks at them they turn there head and ignore eye contact to make it look like they weren't looking at all