Usually a remark about something currently affecting both of us at that moment (like a chilly morning or a long line at the DMV) .. or sometimes a compliment (if I admire someone's hat, pet, scarf, etc.)
Usually, "Hi, how have you been?"
hahahaha Dang it, stop telling my secrets, blabbermouth. lol
Stare at them before saying "Can you see me?"
Do you need to borrow a cup of milk?