Countdown bosses apparently had to axe part of the TV show after an 18-year-old student came up with a swear word.
The Sun reported that Jack Hurst, a Cambridge University maths student, produced the word "s**tface" after he was presented with the letters DTCEIASHF.
A source told the newspaper: "The bizarre thing was he had a spare D - spelling a concept most students are more than familiar with."
Dictionary expert Susie Dent told Countdown host Jeff Stelling that the term for a "rude or obnoxious person" was OK, but Channel 4 said it was "not appropriate" and produced more letters.
Channel 4 said: "Countdown is a daytime programme and this particular word was not deemed appropriate for a daytime audience so not included in the show."
Hurst, 18, won eight shows during his stint on the programme last month, achieving the highest ever total for an "octochamp".
Countdown was the first show broadcast on Channel 4 when it launched in November 1982, and has since become a national institution.