Hey Dad star exposed himself on set: court

When an alleged victim of Hey Dad! star Robert Hughes complained to a cast member about his behaviour, she was told he was "just a dirty old man".

Hughes, 65, has pleaded not guilty to 11 sexual and indecent assault charges stemming from allegations he abused five girls in the 1980s and 1990s.

Speaking at his trial on Monday, one of the alleged victims told Sydney's District Court that she grew to dislike Hughes following a number of alleged incidents on the set of the popular show.

In one instance, sometime around 1990, when she was around 12, she was drawing while she lay outside Hughes' dressing room when he allegedly appeared in front of a mirror.

"He looked at me ... He made eye contact with me and he undid his pants," she said.

After unbuttoning his pants, the actor let them and his underpants fall to the floor, before "wiggling his hips", she said.

"He was looking at me and then looking at his penis."

"It felt like a very long time but I would estimate it was probably 10 to 15 seconds," she added later.

The woman told the court that she "freaked out" and ran away.

When she told one of the cast members, she alleged they "made a joke out of it" and said "he's just a dirty old man, let's make sure you are not near him again".

On another occasion, the woman alleged Hughes pulled her and another young girl onto a sofa bed in his change room and tried to tickle them.

"I kept telling him to get off. He had me pinned down. He was touching me all over ... he kept putting his hand up my shirt," she alleged.

The woman initially denied spitting on the actor while they were on set.

However, minutes later while under cross examination by Hughes' defence lawyer Greg Walsh, she said she "may have" spat at the back of his head.

"You are just making this up, aren't you? ... this is so entrenched that you don't know the lie from the truth," Mr Walsh said.

In relation to the incident in which Hughes allegedly exposed himself, the woman admitted the actor often got changed in that part of the set.

The trial continues.