Guys act strange when walking past?

When i walked into my classroom with only two guys in it at the moment, they were speaking but as soon as i entered they just went quiet and stopped talking.. and then they pretended to sleep with their heads down on the desk and i left the classroom closing the door.. its not like they are rude or anything to me though.. and it has happened a couple of other times in the hall for example when i walked behind two guys and one was making an embarrassing joke, and then the guy saw me walking behind them and alerted his friend to stop pushing him on the shoulder and both went quiet😭😭 personally i dont speak to a lot of people, and one guy in a higher grade knew my full name too even though i didn't know his. I dont know if this stuff is considered negative or not¿

Guys act strange when walking past?
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