Hussain pleaded guilty to the charges
A drink-driver who killed a father and son in a motorway crash was performing a sex act on himself minutes before the collision, a court heard.
Imran Hussain was driving at speeds of up to 120mph minutes before he ploughed into the back of a Fiat Punto carrying the Proctor family, from Wakefield.
Gary Proctor, 47, and son James, 16, died in the smash on the M62 motorway near Rochdale, on 3 August.
Hussain, of Bradford, was jailed for eight years at Manchester Crown Court.
The 32-year-old, of Como Avenue, pleaded guilty to two counts of causing death by dangerous driving and one count of driving with excess alcohol at a previous hearing.
The court heard that Hussain's erect penis was exposed when motorists came to his aid after the crash.
Judge Andrew Blake told him: "At the least it must have been a symptom you were not giving your full attention to driving."
He sentenced him to eight years for each of the two counts of causing death by dangerous driving, to be served concurrently.
Hussain, a car dealer and father-of-four, was also banned from driving for 15 years.
Prosecutor Andrew Nuttall said Hussain had rowed with his wife hours before the crash and left the family home on Como Avenue for a night out with friends in Leeds.
He later stopped at a service station in Leeds in the early hours, where he was described as "staggering and clearly drunk".
When challenged about ripping open a bag of crisps, he told the cashier: "I'll find out where you live and will kill you."
The Proctors were on their way to catch a flight to the US
Police examined his mobile phone and discovered that he had called directory inquiries to request the number of an escort agency about 30 minutes before the crash.
Mr Nuttall said he called the agency - which provides female escorts on an hourly basis - but it was closed.
He said: "His attempts to contact the agency and the finding of him with an erect penis out of his trousers indicates that he was sexually excited and clearly handling his penis whilst he was driving and at the time of the collision."
Hussain's erratic driving in his Audi Q7 was reported to police by three groups of concerned motorists minutes before the crash.
Mr Nuttall said that, moments before the collision, the vehicle was seen lane-hopping, before veering across the carriageway and into the back of the Proctors' Fiat Punto.
Several motorists stopped to help, including Christian Downard and his two friends.
Mr Nuttall said the trio went to help Hussain and saw that his penis was out of his trousers. He tried to run away and hurled abuse.
The Proctors had been travelling to Manchester Airport to fly out to Florida for a family holiday.
Mr Proctor's wife, Catherine, aged 44, survived the crash, but suffered serious rib and arm injuries.
In a statement released by police, Mrs Proctor said no words could describe the devastation her family felt.
"No-one should ever go through the nightmare I have suffered over the last four months," she said.
"My whole life has been shattered. My hopes and dreams for the future have been taken away from me and the rest of my family. We will never recover from this."
Speaking after the hearing, Sgt Phil Robinson, of Greater Manchester Police, said: "This man has taken Catherine Proctor's entire family away from her in one fell swoop.
"Not only had he got behind the wheel of his car when drunk, but he had driven so dangerously it is actually a wonder that he did not ruin anyone else's life that day."