This post brings back memories.
I used to do this all the time when I was in high school actually. Especially if I saw someone that looked down or stressed out from their day. I got the idea from this kid named Mitch who used to always give me a high five when he saw me in the halls. Then there was Franny. The most popular kid in school, and not one person hated him (despite the fact that he was your typical prep/jock). He used to walk down the halls and give everyone that looked down a pat on the back. When he saw his actual friends in the hallway, he'd give them a high five. I wasn't as close to him as his other friends were, but he always gave me a high five when he saw me.
I guess they grew onto me, because I started walking down the hall and giving random people a high five for no reason. Especially if the person looked down or upset. Of course in high school we only had five minutes between classes. So, I usually kept walking. However, on several occasions people would see me around and talk to me like we were already friends. And they only knew me as the guy that gave them a high five in the hallway one day in-between classes. Not only does giving random people a high five seem to break some sort of barrier, but it also seems to put a smile on peoples faces.
By the way, I think some of you are too afraid of looking weird (see: check_mate_kid_uk). However, when you're outgoing, you take those chances. When you're outgoing, you're not afraid of looking weird. You know that being weird can be a good thing!
Another interesting story. Rewind back to high school, again. One day, my mother is having a rummage sell. She's selling two full bags of bouncy balls (the ones you get out of machines for 25 cents) for one dollar. Franny, the kid I was telling you about earlier, made a bet with me. We called it, "The who has more balls challenge". We bought the balls from my mother for a dollar and we came up with a challenge. We would both bring a bag of bouncy balls to school and attempt to sell them. 25 cents per ball. The person who won the challenge would keep all the profit (each bag was worth 10 dollars). Now, selling candy bars is one thing... But selling rubber balls, that's just weird.
The interesting part is how we both acted when we sold them. At first, we both tried to sell them with serious looks on our face and come up with some lame story like "we're trying to raise money for a club". That got a few sells. I was getting bored, he was getting bored... We both wanted to sell our whole bag. So, Franny and I put a smile on our face and start walking up to people with a burst of energy. When people would walk away or ignore us, we'd say "ah, come on. Bouncy balls are fun! And they're cheap, too!". We purposely acted weird since we were selling a weird product in school anyway. Either the person would smile and keep walking or they'd turn back and say "okay, how much?". Sometimes, the person would smile and keep walking, but someone else would overhear us and they'd buy one. In the end, we both sold our whole bag.
The moral to that story is that acting weird isn't really a bad thing. In fact, by acting weird, we made our product seem FUN. And everyone was buying one just because it was the cool thing to do for that day. Around the end, we weren't even trying anymore. People were actually coming up to us and asking for them. Even when we both sold our whole bag, people were still asking for them. Because we made the product seem FUN when we decided to stop acting serious about the competition and acted a little bit weird. It also made US come off as FUNNER people to be around.
P.S. My marketing teacher actually saw me doing this and gave me extra credit points for that, heh.