Peter Small, 26, made the comments in a bid to engage pupils at Parkfield high in Wolverhampton, making one girl cry, England's General Teaching Council heard last week.
The newly-qualified supply teacher had found it difficult to keep order among pupils, so he initiated a classroom game in which they tried to out-do one another by prefacing a shocking sentence with the words "your mother".
Mr Small said he used the words as a shock tactic to engage his pupils' attention. He joined the school in December 2004 and had been told in an assessment to use a greater range of strategies to manage difficult pupils.
Mr Small, who taught religious studies and sociology, was part-way through his induction when a parent complained.
Karen Wild, associate head, met the mother of a Year 8 pupil in June 2005, who said Mr Small swore in front of his class.
She said another teacher had told her he had received similar complaints from two Year 9 pupils some days previously.
Mrs Wild spoke to the children and a Year 9 pupil. One said: "Mr Small often said things in class about our mums and he said some things about one of the boy's sisters, which he did not like.
"He said my mum was fat and made out that he had met her. Some boys thought it was funny."
Another pupil said: "One girl ran out of his class crying. He would say things as a joke but pupils would get angry with him."
Mr Small admitted he had used inappropriate language.
Arthur Thompson, Parkfield's headteacher, said he could not suspend Mr Small because he was employed by an agency. However, it was agreed he would cease working at Parkfield.
The Child Protection Agency was contacted as a result of the sexual nature of some of his comments, but an investigation was dropped.
"I accept I was being unprofessional but I never used such shocking language. I never have and I never would," Mr Small said.
"On occasion I would say things like 'I have to speak to your mother', which would stop them in their tracks with astonishment."
Mr Small said he found the pupils' behaviour challenging. "I received little practical support at the school," he said.
Mr Thompson agreed that Parkfield high was difficult for a new teacher.
"That is why management is crucial," he said.
The reprimand will remain on Mr Small's records for two years. He now teaches at Shelfield sports and community college, Walsall.