That's a no-no means it's not allowed or it's prohibited. Driving drunk, for example, is a huge no-no; cheating on an exam is another major no-no. If you do something that's a no-no, there are usually consequences--meaning, you could get in trouble. You could get arrested when you drive drunk or you could get kicked out of school if you get caught cheating.
If you work in an office, some managers don't allow workers to surf the web while working. If this is the case at your job, you can say, "Surfing the web is a no-no at work; the boss gets very upset when he catches one of us on the Internet."
A: I just got a ticket for parking in front of a fire hydrant.
B: Why did you park in front of a fire hydrant? Didn't you know that's a huge no-no?
A: I did. I was barely in front of it--well, maybe except for my back bumper.
B: Well, the cops can get very picky when it comes to fire hydrants.
A: I know. I thought I could squeeze in there. I'm definitely not doing that again. What if I ignored the ticket and pretended like I hadn't seen it.
B: I wouldn't do that. That's another big no-no. You could get in more trouble. You're actually lucky they didn't tow your car away.
kicked out - expelled; forced out
barely - almost not
picky - strict (in this context)
when it comes to - when we're talking about
tow a car - remove a car from a space using a tow truck
Alright folks, think of a few things that are not allowed at your workplace or your house and make sentences using it's a no-no. Then you can pretend you had no idea they were not allowed and say something like, "You know what, I had no idea wearing sneakers at work was a no-no." or "Did you know leaving dog poop on the sidewalk is a no-no?"
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