Why would a guy keep staring at me during multiple months?

To the shop I go to buy my food there's a worker that literally stare at me every single time I go, when he see me he stop what he do to look at me, I didn't think much of it until my friend commented on it (about how she found him creepy because no matter if I'm far or near he continue to stare hard at me) and last time I caught him staring so I stared back at his face and he kept staring without any shame to my face.

He have been doing this for months like 8 months, I did not think much of it, did not even notice him before my friend commented on it but now I'm kinda creeped out by his stare, dude don't even look away when I caught him, just continue to stare hard at me.

Why would a guy keep staring at me during multiple months?
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