The defence had shown the Newstead woman a flesh-coloured novelty pen, which it claimed was the object that the accused was holding at the time.

Teacher Mark Andrew Tripptree, 47, pleaded not guilty in the Launceston Supreme Court yesterday to two counts of indecency.

The Crown has accused him of having exposed his penis by masturbating in a public place, in two separate incidents, on the morning of March 31, 2012.

Crown prosecutor Patrick Dixon said that the alleged acts occurred while Mr Tripptree was in the driver's seat of his stationary car in Penquite Road, Newstead, and about two hours later in St Leonards Road, St Leonards.

Mr Dixon said the two key Crown witnesses were strangers, but would describe essentially the same modus operandi.

Defence counsel Grant Tucker, in his opening address, denied that his client had ever committed such acts.

Two Crown witnesses gave evidence and both women were adamant of what they had seen Mr Tripptree doing in his car.

The Newstead woman said she had been walking along Penquite Road and had seen a man, through his open car window, holding his flaccid penis.

"It seemed to move faster, the hand that was holding the penis," she said.

The woman agreed with Mr Dixon that the man had bare legs from the waist down.

Under cross-examination, the Newstead woman agreed with Mr Tucker's suggestion that the man's penis was hanging over his fist.

"I could tell he was circumcised, that's how much I saw," she said.

The second Crown witness, a St Leonards woman, gave evidence that she had been waiting at a bus stop in St Leonards Road.

She said a driver pulled up his car near her and the man asked her for directions to the St Leonards sportsgrounds.

The woman said she bent down, looked through the open car window and saw the man's trousers were down to his knees.

She said the man was using his right arm to masturbate.

The trial before Justice Robert Pearce continues.