Channel 4 is being probed by the media watchdog after a lewd comment made by comic David Walliams on one of its shows sparked a number of complaints.
Ofcom said it was "assessing" if the joke, in which the Little Britain star said he would like to perform a sexual act on a teenage member of boy band One Direction, had breached the broadcasting code.
Walliams, 40, was appearing on Chris Moyles's'Quiz Night' at the end of last month when he made the sexual remark to the Radio 1 DJ.
During the show, which was aired an hour after the watershed at 10pm, Walliams agreed with Moyles that he liked 17-year-old singer Harry Styles "because of his hair", before adding: "I would like to [perform oral sex]."
According to The Sunday Times, Channel 4 received four complaints from viewers, while Ofcom received two.
An Ofcom spokesman said: "We will assess the complaints against the Broadcasting Code, the rule book of standards which broadcasters must adhere to."
Channel 4 said the show was aired post-watershed and that viewers had been warned of strong language and adult humour.