Not every obnoxious workplace behavior is unlawful harassment. To violate federal law, the harassment has to be unwelcome, based on a "protected category" (for example, sex or race), and "severe or pervasive."

But most employers aren't satisfied with banning only "illegal" behavior, and rightfully not. The law does a fairly good job of keeping us from each other's throats. But it doesn't mandate that we be nice, or even courteous, to each other. That's what company policies and good manners are for.

There are a lot of workplace behaviors which, although technically not "unlawful harassment," are likely to get an employee accused of, fired for, or even sued for, unlawful harassment. Here are my top five "high-risk" behaviors:

No. 1: Having an extramarital affair with a co-worker. How can this be? Harassment has to be "unwelcome," doesn't it? If you're having an affair, doesn't that mean both parties are willing participants? Well, yes. But it's still risky business. Here's why:

There are not "two parties" to an extramarital affair. There are at least three, or four if both parties are married. (Not to mention kids, extended family, close friends, lawyers, and private investigators.) When you consider the spouses as well as the lovers, it becomes obvious that there is no outcome to an affair that is going to be good for everyone. Either the parties to the affair decide to leave their spouses and get married, which means the jilted spouses are hurt, angry, and sometimes vindictive or unstable -- or one party decides to go back to his or her spouse, which means the jilted partner in the affair is hurt, angry, and sometimes vindictive or unstable.

https://www.youtube.com/watch?v=48DN8QWVAJg

It's the "vindictive/unstable" part that is the most likely to create the risk of a harassment complaint. Here's one scenario that occurs fairly often in real life: Husband finds out that his wife was having an affair with her supervisor, is irate, and threatens to get a divorce and take the kids and all the money. Maybe even sue her for alimony. How does she calm her husband down? The easiest way out is to accuse the supervisor of sexual harassment. Then the husband's fury is directed at the supervisor, and not his wife. Problem solved! (Except for the supervisor, whose problems are just beginning . . .)

Or how about this one? Co-workers are having an affair. The woman decides that it's a mistake, and she breaks up and tells her partner that she is going back to her husband. Partner is devastated, and begins stalking woman and calling her at all hours. When woman threatens to call the police, heartbroken partner turns mean and goes to HR and accuses her of sexual harassment.

Or this: Co-workers are having an affair, and they send "playful" sexual emails to each other using the company system. Both parties are probably in violation of the company's computer use policy, and they're likely to be fired over it.

No. 2: Telling sexual, racial, or ethnic jokes to co-workers who you know will think they're funny. If you think the jokes are funny, and your co-workers think they're funny, then what's the problem? I can think of three problems right off the bat: (1) We never know what other people really think, even if we think we know what they think, (2) a third party may overhear the jokes, and may not share your sense of "humor," or (3) your co-workers did indeed find your jokes hilarious, but a few months later they got mad at you for something unrelated, and they reported you and your jokes to HR out of spite.

No. 3: Using gender-specific or "sexual" curse words. That guy who's just being a "d**k." Or the wimp who is a "p**sy." Or that argumentative woman who is a "b***h." And "f**k" this dead-end job, anyway. How can these expletives be "harassment"? You didn't mean them in a sexual way. True, but the words all have sexual associations and may be viewed as "harassing" by your co-workers. In addition, when you call a difficult woman a "b***h," you are sorta making a comment about her gender in addition to her unpleasant personality. So watch out for the way you cuss at work. If you must cuss, you are better off using words that are not associated with gender or sex acts. (But note: If you direct all of your cursing to members of one particular racial or ethnic group, or of one gender, you could be guilty of actual harassment even if your words are "gender-neutral.")

https://www.youtube.com/watch?v=TH_JRjJtNSw

No. 4: Talking about politics or religion at work. There is an old etiquette rule that one should not discuss politics or religion in polite company. The rationale is that people disagree vehemently on these topics, and so such a discussion is unlikely to create a socially pleasant environment.

I am pro-First Amendment, and I love arguing about politics and religion. But I still believe that the etiquette rule is a good one to follow at work. There are two political topics that I have seen turn into lawsuits in real life: (1) whether women should work outside the home, and (2) whether affirmative action is a good idea. I'd add one more to the list based on recent events, although I haven't seen any litigation result from it (yet): immigration policy. Also watch out if your religious beliefs are so strong that you feel compelled to tell your co-workers they'll suffer eternal damnation if they don't repent ASAP -- or if your lack of belief is so strong that you feel compelled to tell your religious co-workers that they're a bunch of suckers who believe in fairy tales.

The First Amendment means only that the government can't infringe on your rights of free speech or freedom of religion. Unless you work in the public sector, the First Amendment doesn't control what your employer -- or your offended co-workers -- can do.

No. 5: Injudicious use of social media. If you are Facebook "friends" with your co-workers, then you need to watch what you say on Facebook. The same goes for other social media platforms. Keep in mind who will be reading what you post, and post accordingly. I'd even recommend being careful with "likes." If this is too stifling to your personality, then don't be friends with or followers of anyone you work with. You might also want to make sure your privacy settings are adjusted properly. And re-check them on a regular basis, because Facebook changes the rules about once a week.