What does it mean when a guy keeps looking back?

alisson
OK so I was at this "gathering" thing with all of my friends(we hadn't seen each other since 5months) for the group trip. so I looked diff. and there was this guy (friend)that was in front of me and he kept looking back at me every 1minute. I was just wondering why? and don't say well it's obv. 'cause I know he doesn't like me or so I think and I didn't have anything on my face either
What does it mean when a guy keeps looking back?
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