My 15-year-old son keeps telling me to f-off if I ask him to do anything he doesn't want to do - get up, get off the computer, go to bed.
My partner says it doesn't mean anything and I should just ignore it. But I hate it. It makes me feel useless and angry.
There's a lot more swearing around than there used to be. It's in films and on TV. Musicians swear. People even swear at work. I did a temporary job in an all-female office last year, and my boss was f-ing this and f-ing that the whole day long. But even though we're surrounded by it on a daily basis, most of us know there are rules to follow. We know exactly when to keep our mouths zipped.
"Sometimes I hear my son when he's in his room with his friends," says one mum I know, "and I'm shocked at the language they use. But they never swear when they think I can hear. So I just ignore it."
The rules go something like this.
You don't swear in front of anyone who's in a position of authority (your boss, a police officer), in case they get cross and punish you (fire you, arrest you).
You don't swear if you're with someone who you don't know very well (in case they're offended by it).
And you probably don't swear in front of someone who's elderly unless you know they're going to find it funny.
So swearing is complicated. It can be a way of joking around with your mates. But in different company it can be read as aggressive and showing a lack of respect.
In some families, where everyone is swearing all the time, it might not mean very much if a teenager swears at his mum. In other families it would be deeply shocking. So this is probably the first thing to work out. If you're upset and angry, does your son know how he makes you feel? Is he trying to hurt you? Or is he blissfully unaware of the effect his swearing has on you?
According to the brilliant book Blame My Brain (Walker Books, £5.99) by Nicola Morgan. during the teenage years the frontal cortex - the part of the brain that has most to do with thinking, reasoning, logic and decision-making - goes through massive changes. It doesn't settle down again until about the age of 17.
During these crucial years, teenagers might be relying more on the amygdala, the part of the brain that's linked to gut reaction and raw emotion. So swearing - which is emotional, very impulsive behaviour - may just be the result of a brain that's still a work in process.
But knowing this doesn't necessarily make you feel any better when your 15-year-old son tells you to f-off.
A friend of mine with teenage boys once said that she didn't feel it was OK for any of her sons to make her feel uncomfortable in her own house. Personally, I think that's a good rule to follow. While it's sometimes better, if you're the parent of a teenager, to say nothing and let it all wash over you, at other times it's important to clear the air.
So if you're really uncomfortable with your 15-year-old son swearing at you, what should you do?
Dr Rachel Andrew, a clinical psychologist who specialises in children and families, says: "The first thing is to take a step back, and think about why your son is responding like this. Is it just that he doesn't want to do the thing you've asked him to do? It could be that he feels you're on his back all the time.
"But sometimes something that seems quite straightforward on the surface could be more complicated underneath. Is he looking for a certain reaction? Is there something else that's making him really angry with you?
"It's possible, if you're not reacting really strongly when he swears at you, that he's not aware of the effect it's having on you. But it's also possible that he knows precisely what he's doing. So maybe I'd say to him, 'I find this really upsetting. What's it about? Is it the things I'm asking you to do? Or are there other things going on?' It may go nowhere, but at least it gives you an opportunity to talk.
"Your partner's response is interesting. By being really laid-back, he's forcing you to be the disciplinarian. Maybe you should talk to your partner and try to find some middle ground. If your partner took on some of the role of disciplining your son, you might feel much less isolated."
Teenage swearing is relatively common. But what matters is the way it makes you feel. If your 15-year-old son is communicating in a way that upsets you, it's probably time for all of you in the family to start talking about it.
More on Parentdish: How can I stop my child swearing?