Then Nokulunga - known as Lunga, or, more flamboyantly, Snake-Girl - puts the other one back. Now both feet are on her head.
At school, Lunga says she interrupted lessons to show the teacher her moves, and at break times she did demonstrations for her classmates - and charged them for the privilege. (Her brother, Bheki, collected the money and they spent it on sweets.)
I wonder if the snake-child was bullied - like the fat kid, or the clever kid, or the, well, freak kid. But no. Lunga is beautiful and confident, and this surely helped.
"All the other kids wished they were as flexible as me." She gives a proud smile. "But only I could do it."
Like her great-grandmother, Lunga might have stayed an amateur snake-woman. But one day, when Lunga was seven, her mother Nokuthula met a gymnast called Sylvester performing in the local shopping mall, and she told him about her incredible bending daughter.
"He came round and saw me, and he realised I didn't need any training to be a contortionist," she says.
Sylvester took her to auditions for the UniverSoul Circus, which was recruiting in South Africa. They took her on instantly, but insisted she go to circus school in Cape Town to sort out her routine, which in Lunga's case meant simply rolling her moves into a seven minute sequence.
When she was ready, she was literally taken away to join the circus - every English child's bedtime fantasy - in America. She had a chaperone called Catherine, and she did her lessons between hours on the sawdust, returning home every three months to see her family, whom she was already supporting financially.
Today, she earns about £50,000 a year - top whack for circus performers and the going rate for a photogenic snake-girl.
£I had never left my family before so it was pretty difficult," she says. "But I got used to it." And it was wonderful, she says, growing up in a Big Top.
She used to ride on the elephants' backs, and even polish their toenails. When a tiger escaped from its cage, she says, it padded backstage and eyeballed her.
It must have been the oddest of childhoods, and being a snake-girl had trials all of its own.
"I was only nine when all these responsibilities came crashing down on my head," she says. "I always wanted to go to a real school, and I never will now. It's nice to travel the world, but sometimes I wish I had done the things other teenagers do - go to school, play truant, get into trouble, sneak off to the movies. Just have fun.
"And it would have been nice to have people my own age around me. I was always the youngest."
Neither, she says, does she have time for that other rite of teenage passage, a boyfriend.
And as the circus people pop in and out of the office, I realise she is a bit of a pet. They kiss her, and pat her, and treat her like a (child) star.
This explains her strange combination of sophistication and naivete. "I was always a tomboy," she says. "I was never girlie. I never liked Barbie."
Of course she didn't. Barbie is for girls growing up in the suburbs and dreaming of something more interesting - not for tiny snake-girls taking their bows.
"Although," and she sits up straight as she says this, "I am trying to be like a lady."
She is also continuing her studies by correspondence course between shows, but she doesn't know when she will retire.
"I have seen contortionists in their 70s," she tells me, "so who knows how long I will do it for?"
How does a snake-girl maintain herself? She says she eats very healthily: no carbohydrates, hardly any meat, and chocolate only once a week.
"I have to keep my weight straight," she adds, adding, very tactfully: "My mother is not a small person."
Are there any fat contortionists? "There are fat contortionists," she says, "but it doesn't look attractive, because you wear very tight costumes."
She joined Africa! Afrika! two years ago, when she was 16. When they were in Frankfurt, Lunga went to see a specialist about her 'flexibility' and he X-rayed her in a contortion position.
"He said I am as normal as everyone else. I am just more flexible."
Even when she occasionally makes a mistake in her act, she never falls, and she has never injured herself. Her super-bendy body just carries her through.
"If I fall, everyone thinks it is a new trick," she says.
She loves being snake-girl. "I like to torture people with it," she says. "People scream and cry when I do my act. A lot of them think it is disgusting."
She seems rather thrilled by this. "I am different. And I like to be different."
She certainly is. But doesn't she ever wish it would go away and she could be normal? "Even if I wanted it to leave, it wouldn't," she says, adding vaguely: "I still contort in my sleep.
"It isn't nice to be compared to a snake. The flexibility of a snake is very good: but the other characteristics are the worst."
She falls to the floor and does her snake act. Her body seems to be made of rubber. She melts, bending her legs over her head, tucking her hands and feet into places non-snake-girls simply cannot reach. It does look wildly creepy, even disgusting.
And she chatters away, bending herself over again. "People always ask me: 'How do you do this?' But I don't know. Nobody knows. Only God knows."
"Do you know," she adds, "that I can't do a straight hand-stand? I'm too flexible." And, smiling at me like a child with an incredible toy, she sticks her foot on her head. Again.
