I often get approached when I go slinging; people love to watch, and sometimes even try it.
Most of my expirences have been great, and I've heard some cool stories already.
I was wondering if anyone would like to share.
A few of my stories:
I once went head to head with a lacross player (very in shape) and got better distance than him with my sling.

A professor (I think) became ecstatic, when he saw my friend and I slinging, and didn't want to put the sling down. He was a natural.

A fair number of girls from a swim team giggled the whole time they sling water ballons at eachother.

My favorite, one of the officers at my range was collecting his arrows, when  I accidently sent a tennis ball veering far to the left, and past a barrier. Someone screamed "Look out!", I thought I was toast. He came back with a limp and a grin saying "Is this your ball?".

-Unsapien

i thought he was joking... ???

This doesn't have to do with slinging, but last year I was asked one of the dumbest questions ever. After I had told someone that I had moved to the US half a year ago they asked me "Did you know English before you came here?" I think I came up with some sort of witty sarcastic reply

Turkey (ever heard of Istanbul?)

It's also rather close to Byzantium

He was joking; I don't think he got hit hard.
Most of the force had been dispersed by the time it hit him.
However, the tennis balls I use are weighted
As an extension of the water-bomb project I decided to experiment with tennis balls. I injected them with water using a siring. These weighted tennis balls are commonly referred to as "H2O balls" by my friends. Although these H2O balls tend to have a point were they suddenly loose their velocity, they hit decently hard.

I use these while at the range for a number of reasons.
Pro:
1) They tend to damage the target less due to their surface area.
2) They are uniform in weight.
3) Can be easily found because of their bright color.
4) Appear less threatening than rocks to other people.
5) Good for new slingers, and new techniques

Con:
1) Bounces off hard targets
2) Can cause serious bruises
3) Are much slower than rocks
4) Do not have the range of rocks.
5) Need to be made

I will say however these tennis balls sometimes hurt when you try to catch them.
I was stupid enough to sling at my friend while he wasn't looking (DO NOT SLING THESE AT PEOPLE!), and I believe I badly bruised him.
I carry both rocks and H2O balls with me at the range; I generally sling the H2O balls when people are close to me.

-Unsapien

my dad doesn't know i'm starting with slinging

i think if he knew, he would look at me like i'm crazy or somethin' 

my brother doesn't care, taiki wanted to learn him how to sling, but he refused 

I don't go slinging often, so I don't have many cool stories: people don't use to watch and lets not talk about approaching 

But I got my grandpa into slinging this summer after nearly 50 years without touching a sling. It was a funny afternoon with both of us trying not to hit ourselves.