Most people teach their children not to talk to strangers. I feel that even adults will avoid talking, smiling and joking around with a person just because they have never met them before. Why assume that the person is BAD, when you could assume the person is GOOD. Look them in the eye, look at what they are wearing, count their piercings and tattoos, then talk to them anyway.
When I was raising my young child I taught him to be cautious who you talk to. I would never tell a child not to talk to strangers. The person behind the counter is a stranger, but you have to talk to them and you can't tell your children that "all shopkeepers are good" because it just isn't true. At least, you don't know if it is. Do you want your child to have an automatic trust of all shopkeepers? No, you don't, or you shouldn't.
We have learned that it's the people who hold positions of automatic trust that are the most likely to be offenders. You've heard the hockey coach, the priest, the scout master, the babysitter, the teacher, the doctor etc have all been charged with molestation. Yet, you've told your child to talk to them, trust them and follow their instruction, why? We are afraid to talk to good and honest regular people, yet we'll place our children in harms way every day of our lives. Our kids are in hockey, at the doctor, in the church and at scouts, every day, with no supervision. Why do we trust the hockey coach, yet shy away from the person in line in front of us at the grocery store. Everyone look down, that'll make the line faster, that'll make your day brighter.
Is there harm in casual, meaningless conversation with a stranger? If the person makes you uncomfortable, talk to someone else, if everyone makes you uncomfortable, see your doctor. I believe it's good health to make a point of talking to a total stranger every day.
Conversation starters by GG:
"Hey, does this chicken look fresh to you?" (But you have to NOT be holding chicken, never ask that if you have chicken, because it'll just be stupid)
"Wow, you'd think this liquor store would be busier. It being a Monday and all"
"Is my deodorant working?"
Truthfully, the above will only make more people avoid strangers, so maybe try these instead:
"Hi, did you see the sale in aisle three?" But you have to really have a good sale in aisle three, or it'll just be stupid. Like half price water or old people diapers, you know.
"mmm, ingredients for lasagna, nummy"
"wow, you found that top here?"
"Hey, I am about to feed ten people, do you think this is enough potatoes?"
"These grapes any good? here eat one"
Oh, another fave, if a group of people are talking about one of their friends, and especially if it's a particularly bad story, always, always, ask if he's single.