A maths teacher was caught hiding under his female pupil's bed by the teenager's mother in Bolton.
The woman, who had surprised her 16-year-old daughter by returning home early for lunch, was described as "shocked" by The Sun at the discovery.
The 35-year-old man was found lurking under the teenager's bed during a search of her room by the suspicious parent.
After the teacher was pulled out from where he had been cowering, the police were called to the house and the man was taken into custody.
A source told The Sun: "The pair had gone back to the girl's house because they thought no-one would be there.
"But the mum came home earlier than expected and caught them.
"She went into her daughter's room and found the teacher hiding under the bed. It was a terrible shock. I think she had only come home to grab some lunch. The mum went berserk."
Greater Manchester Police are now investigating, a spokesman said.
"Police were called to an address in the Bolton area following concerns for the welfare of the 16-year-old girl who lives at the address. Officers attended and later that day a 35-year-old man was arrested on suspicion of abusing a position of trust.
"He has been bailed until 15 August 2013 pending further inquiries.
"Greater Manchester Police officers and a number of partner agencies in the Bolton area are investigating the circumstances leading up to the incident itself.
"This investigation will also look at any safeguarding issues that need to be addressed and establish if any offences have been committed."