Guys, why would a guy act like you don't exist, he avoids making eye contact and avoid talking to you when he even doesn't know you?

I just went there to get services, he adjust his shirt when i look at him. And asks tea from my friend but avoid looking at me and asking me.

Guys, why would a guy act like you don't exist, he avoids making eye contact and avoid talking to you when he even doesn't know you?
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