Comedian Joan Rivers stunned TV viewers in the U.S. on Tuesday by smoking marijuana on her reality show.

The veteran funnywoman was shown obtaining medicinal cannabis from a dispensary in California before puffing it from a pipe while sitting in her car with a pal.

As the effect of the drug takes hold, she then dissolves into fits of giggles and has to be driven home by a friend - stopping on the way to pick up burgers and fries.

But Rivers' pot-puffing antics infuriated her daughter Melissa, who told viewers, "My 78-year-old mother has now become 17, and I have become a soccer mum yelling at her teenage kid."

The scenes were broadcast on network WETV's reality show Joan & Melissa: Joan Knows Best.