The Crown says he told them his name was Jack and that he was a social worker in his early 20s.
"He lied about his name, age, and occupation," South said.
He is accused of again offering to buy them food before taking them for another ride in his van.
The man also allegedly took them shopping, bought them clothes, a phone charger, and lollies.
He then allegedly offered them the chance to stay at his house for the night, which was "quite an appealing proposition" for the troubled youths - some of whom didn't go home at night to sleep, the court heard.
The man is then accused of driving them to a drug dealer and giving them about $100 to buy cannabis.
He then allegedly took them back to his house where the young teens "smoked a very substantial amount". The accused did not partake at all, the court heard.
When it came time for sleep, the defendant allegedly insisted that they all sleep in one bedroom, despite the Crown saying there was plenty of room in the house.
Two boys "very intoxicated with cannabis" slept in the same bed as him.
One of them woke in the night to find his trousers and underwear halfway down his body and the defendant allegedly lying "very closely" beside him, with his hands "rubbing" his leg.
Afterwards, the Crown alleges that the accused contacted the mother of the boy he had allegedly touched to make some "counter allegations", including claims that the boy was a drug dealer, that he was gay, and that he'd been making allegations against the man.
The Crown say the man's actions were not that of a kind-hearted social worker, but instead amounted to "sinister behaviour".
The man denies four charges, which include meeting a young person after grooming, two charges of aiding the supply of cannabis to children under 18, and indecently assaulting a 13-year-old boy.
Defence counsel Andrew McCormick made a brief opening statement today to urge the jury of seven women and five men to remain dispassionate, to put aside any feelings of sympathy or prejudice, and to look at the evidence critically.
The trial, before Judge Paul Kellar, continues.