The Big Bang Theory has been heavily censored in UK airings of the show, due to different TV guidelines. In the UK, The Big Bang Theory airs on the channel E4 and, secondarily Channel 4. Lots of lines or even entire scenes are removed in order to meet UK TV guidelines. This happens because The Big Bang Theory typically airs on E4 before the "watershed" (a phenomenon on British TV channels where content showing before 9:00 pm has to be kept clean of adult content).