Recently, a man named Leslie Brewer was on a street in Greenville, S.C. when comedian Amy Schumer jogged by. He began recording her with his phone. Schumer asked him to stop. He did not. For a few days, you could could see a video of their encounter on Brewer's Instagram. In it, Schumer is protesting over Brewer's shoulder while Brewer, half in the frame, smiles and manages an unapologetic "sorry." His caption: "Amy schumer just got mad at me and cussed me out lol!!! Awesome."

Maybe you are unsympathetic to a wealthy celebrity having her request for privacy--and her personal space--violated by some guy with a phone. But like Schumer, you and I have likely had photos or videos of us posted to social media without our consent. We may not be famous. But ubiquitous gadgets, social media and Wi-Fi have made us all public figures: Others have the power to offer us up for general consumption, and there is little we can do about it.

But there is more at stake now than privacy from each other. After the Snowden leaks, we became alarmed at how much the National Security Agency and local law enforcement know about our lives. (Recently, the former has admitted to sharing information on non-terrorist criminal activity with the latter--all gathered without a warrant.)

You should assume that every time you post photos, videos or personal information about yourself or someone else online, you are also tagging Big Brother. And it's not just the government. There's a saying in business: Data is the new oil. That would be our information: what groceries we order, what movies we stream, who we date or marry (and how often we break up), where we drive for dinner, how many miles we run, the sneakers we buy, and on and on. Governments and corporations pay massive amounts to software startups to create more efficient ways of harvesting the seeds we scatter with abandon around the Internet.

As image recognition APIs and apps improve, posting someone's likeness is becoming tantamount to naming them. To the delight of these corporate and government entities, we have become spies and enablers of spying, invaders of privacy and proliferators of competitive intelligence.

And we do it for free. Once upon a time, paparazzi got paid for snapping the rich and famous in candid moments. Screenshots and clips from the Schumer video have been used by the likes of Entertainment Weekly, People, "TODAY" and "Good Morning America." I don't know what dollar amount Leslie Brewer would put on generating content for all those news outlets--especially now that he says he's been on the receiving end of death threats and cyber bullying--but I'd bet you the contents of your Google search history that he didn't get it.

Brewer, whose Instagram is now private, is hardly a worst-case offender or an outlier. Most of us have seen the memes based on photos of unsuspecting people taken on the subway, for example, or profiles that have been lifted from online dating web sites. Technology evolves faster than we can establish acceptable social norms to manage it. The government and private sector, by contrast, do a fine job keeping up with ways to exploit and monetize the things we share.

My friend and online privacy expert Andy Kahl noted that while there are arguably legitimate commercial uses for the data collected on us, "average folks don't have access to the black box in which companies (and governments) use that data to make decisions we can't influence at all."

For example, Andy says, someone might have a shopping history that includes a lot of Doc Marten boots: "That person might say, 'That's no big deal: Why would I care who knows I like those shoes?' But it's only no big deal until an algorithm somewhere decides that's an indicator of Neo-Nazism."

Thinking about what you share on social media doesn't give you control over all of the data being gathered on you, but not knowing how this information gets used should give you extreme pause when sharing anything at all about other people.

As highly incentivized parties get better at mining our information, we are the biggest threats to our own and to each other's privacy, which are ultimately synonymous. We would all benefit by sharing with caution, not entitlement. Here are just a few ways to behave responsibly on social media:

1) Get enthusiastic consent before posting identifying photos of people.

This would exclude images taken in an earnest newsgathering capacity--Amy Schumer jogging doesn't count--or documenting some criminal activity or abuse. It should go without saying that you always ask parents before posting photos of minors.

2) Don't share photos or videos that you know were obtained without the subject's permission.

You might even consider reporting those that were.

3) Get enthusiastic consent before tagging someone's name or location.

On Facebook, even if the photo doesn't show up on the person's timeline, facial recognition software is still hard at work. Plus, your friend might not want everyone to know when she isn't at home and where she's been.

Also, remember that on social media, your privacy settings are only as strong as those for the pages on which you post.