Ever watchful
Here’s another story that shows why you should always exercise constant vigilance, even when in the safety of crowds. While at a college party, the OP spotted two dudes that definitely didn’t belong. For one thing, they were way older than everyone else.
Secondly, they weren’t smiling or talking to anyone else. One other partygoer accused the men of feeling on their back. It turned out they weren’t there to party, but rather they were there to rob people of their wallets and phones. They stabbed the guy who found them out, but he survived. Be careful out there, folks.