It is a bloody conundrum. Driven to distraction by pupil misbehaviour, the teacher responds with a well-chosen expletive. Suddenly there is a deep intake of teenage breath.
Teachers in the TES online staffroom are currently debating how best to react when they accidentally swear in front of a pupil.
Frustrated by a Year 6 pupil who refused to stop playing with some balloons, one contributor finally snapped at him to "stop messing with those bloody balloons".
The first instinct is to cover up all evidence. One contributor advised:
"Deny it. I swear ataround them quite often. When I said 'just bloody shut up', one kid told me he would tell the head. So I merely pointed out that the head would probably believe me over him."
Others also recommended maintaining innocence: "Say you said 'ruddy balloons', but the words got mixed up."
But some contributors were unsure of the wisdom of compounding bad language with lies. One said: "What alarms me is that teachers are advising that you lie to children. This to my mind is immoral behaviour."
Others suggest that immorality is relative: what difference does a "bloody" make, when pupils often use much stronger language themselves?
Alternatively, pupils will object to the language of even the most puritanical teachers. One contributor told a nagging pupil to wait "two secs", only to be greeted with the response: "Miss said 'sex'."
Often, the only solution is to out-bugger the little buggers. One teacher tells of a pupil who called her a "fucking bitch". She replied: "No I'm not. I'm a fucking evil bitch." The girl never bothered her again.
And, if all else fails, pupils can be reminded that it is not only the teachers who make faux pas. A contributor volunteered to take Year 9 for personal, health and social education. As she walked in, a boy yelled: "Are we having sex with you, Miss?"