awkward moments at work

you know how whenever you're at work and you pass Linda (and why are there so many Linda's at every job? I've never known a real life Linda. I think they're hired by every company to fill some sort of name quota. I don't know why this would be, I just find it odd), then you pass her again like 20 minutes later...? do you say hi again, or do you do that head nod thing, or do you do the eyebrow lift along with the lip seal (sort of a half smile), or do you make some lame joke (workin' hard or hardly workin?)... what in the world do people do? i hate this. It's sort of like when I come back from lunch. I feel like I have to re-greet everyone I just left a half hour ago. "Thank God, it's so good to see you. I was worried you might not make it back from your trip to BK across the street. So how's your life been for the last hour? You still single?"