For reference, I am a 17 y/o male in my Junior year of HS.
So there's a kid in my class, not sure the age but I know he's a Junior (looks like a Freshman though), let's call him Andrew. Andrew usually never talks, and tends to listen in on others conversations, then laugh while looking in their direction.
In this class, my teacher recently set up table groups where we can choose who to sit with, so I chose a table in the back with a good friend of mine (we were the only two at the table). Recently, my friend has been sick so I've been alone at this table for about two classes, and just on Monday, Andrew decided to sit at my table and I'm not sure why, because there were plenty of other seats for him to sit at. I figured there wasn't anything wrong with him sitting there, but he's been creeping me the hell out for the last two classes.
He just sits there on his chromebook the whole class and randomly bursts out laughing hysterically while staring at me, and sometimes I just look out of the corner of my eye and, again, he's staring at me. Even worse, sometimes he is doing what appears to be the "Heil Hitler" salute while staring at me and smiling.
The worst of it, however, is this: on Monday, I brought a protein shake to school that is actually quite disgusting, and most people wouldn't drink it (I do because I need extra energy throughout the day). When I was drinking it on Monday, Andrew just kind of looked at me, and appeared to type something on his Chromebook. Fast-forward to today, and he's doing the exact same things as Monday, but this time he brings THE EXACT SAME DRINK to school that I drank on Monday, and drinks the whole thing at once while staring at me.
I don't know what to do, because I don't want to move seats and it's rude to ask someone else to move. Do I tell the teacher? The school? I'm worried that it's going to get worse. What should I do?
UPDATE: We just got new seats in class and I sit next to him...
UPDATE 2: It turns out he was pretty normal as of a few years ago and was involved in an accident.