Radio stations have been warned about playing songs that contain offensive language following a number of slip-ups.
One station was reprimanded by broadcasting watchdog Ofcom this year for playing the Fatboy Slim song Star 69, which contained 41 instances of the phrase "what the f***", at around 7.30am.
Another played Tinie Tempah's Pass Out in the daytime, containing five instances of the word "f******".
Ofcom has warned broadcasters that "in general listeners do not expect to hear strong language during the day on radio", regardless of whether children might hear it.
Ofcom has also issued a warning to broadcasters to protect children from songs that refer to drugs and sex.
It said: "Radio broadcasters should avoid broadcasting lyrics that clearly focus on the taking of drugs, sexual acts or behaviour, or convey a clearly sexualised theme, when children are particularly likely to be listening."
It said that the broadcasting of offensive language when children are likely to be listening has "frequently been the focus of complaints".
The regulator wants broadcasters to be more careful about live music and interviews.
This summer, Radio 1's Big Weekend was the subject of an Ofcom investigation because of swearing from the Black Eyed Peas set. Radio 1 issued warnings and also apologised for the broadcast.
Last year, BBC station Radio 5 Live was criticised by the watchdog for letting US band Rage Against The Machine swear four times on its breakfast show before they were faded out by a producer.