How do you know if a guy is checking you out?

So today, I was at the mall with a friend and I had to go to the restroom. I told my friend and we agreed to meet up at Victoria Secret after I was done. When I was leaving the restroom, I was walking past a group of boys and as I walked past, I think I heard one of them say “that shit fat (meaning my ass)” but I wasn’t sure if it was that or if they said “that chick fat” and just slurred their words together by accident (I distinctly remember a ‘sh’ sound). Anyways, that got me wondering how can you tell if a guy is checking you out (also I know the only guys who can really tell me what they said is them but if you could tell me what you think they said, that’d be great😂)?

How do you know if a guy is checking you out?
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