Actor Liam Hemsworth suffered the ultimate humiliation in high school - his mum taught the sex education classes.

The Hunger Games star admits he skipped most of the courses because he could not handle hearing his mum share her carnal knowledge.

He tells U.S. late night Tv host Jay Leno, "It's exactly what you think it's like, really uncomfortable... That's when I just head out the door like, 'I'll see you later mum, I'll see you at home'.

"I think out of embarrassment she passed me, but I honestly got so uncomfortable... My mum's such a nice person... I don't know why anyone allowed it to happen. No child should have to be taught sex education by their mum."