A man was so stoned on cannabis that he could not even stay awake for his mugshot, police in Houston have reported.

20-year-old Christopher Shirley was arrested after getting high on synthetic pot before driving to Wal-Mart. He managed to make it to the store's car park before passing out. However, his truck reversed while he was still asleep at the wheel. The vehicle came to a stop after hitting a parked car.

After being brought into the police station, Shirley was still under the effects of cannabis and was unable to stay awake for his mugshot,

According to the arrest report Deputy Jim Slack said: "He was slurring his speech and it just wasn't making any sense. He'd wake up, kind of look around and then nod off again totally out of it. I thought, man, this guy is really high on something."

Shirley was subsequently charged with Driving While Intoxicated (DWI).