On a quiet Wednesday night which marks the precipice between a serious work week and a weekend of bar crawling, a man drives around the city, handing out condoms.
He is dressed in a mock military uniform, with badges, ribbons and whistles and a peaked cap bearing the words "King of Condom".
From offices to street corners and brothels, the self-proclaimed King of Condoms is at home everywhere. He is sometimes hired by corporates to speak to workers at HIV/Aids workshops but this night, sex workers make his audience. They come out in their numbers, some dressed to the nines, but most in jeans and sweatshirts, because of the June cold.
When the King of Condoms spots them, he slows down and calls out softly: "Hey, pretty lady, want some condoms?"
And they light up when they see him. But he goes beyond just dishing out the French letters. He gives health advice too. He notices if the girls are unwell and refers them to the LVCT clinic where he works."We encourage the girls to get tested every three months. Most of them are HIV negative," he says.
"Those with the virus in many cases have got it from long term boyfriends with whom they don't think they need to use protection."
This is the world that Mr Stanley Ngara lives. For more than two decades, he has reached out to the groups at most risk of contracting HIV, teaching them about safe sex and giving them the most important tools towards maintaining a HIV-negative status; information and condoms.
It is a job that requires brazenness and chutzpah. Mr Ngara talks about sex in stark, unembellished terms. At some point, I watch him demonstrate to a group of sex workers how to put a condom on a piece of rubber shaped like a penis.
"Look, you can't bring shyness or timidity towards sex to people who engage in it for a living. For them to trust you and accept your message, you must blur the boundaries of what is considered good manners," he says.
True enough, as Mr Ngara interacts with the girls, I will be witness to shocking language and ribald gestures, all delivered with humour.
He is knowledgeable, non-judgemental and listens patiently while the girls tell him their problems: Vaginal itching and foul discharge, clients that refuse to pay and harassment by police.
CITY CENTRE"Make sure you get tested so that we can treat whatever that is," he says to one.
We traverse only a small part of Nairobi, concentrating on the areas close to City Centre. He jokingly appoints me his assistant and gives me his King of Condom cap to wear. We start from Hurlingham, a few metres from the LVCT clinic where we pick a huge box that has more than 7,000 condoms.
We make our way to Westlands, favouring the less crowded streets which the girls and their clients prefer. Next stop is Ngara, through Parklands.
Finally we end up in downtown Nairobi, where the sex is much cheaper and there are fewer frills. By the time we are done, all but around 200 condoms are left.
Wednesday is a slow night.
In downtown CBD, police officers herd the into a lorry and threaten to lock them up. Or perhaps we should call it a shakedown, really, as it is commonly known that freedom is a few hundred shillings away- or a quick stolen sexual encounter in a dark alley while other officers pretend not to watch.
In Kenya, the law penalises sex work. Men found to engage in prostitution are guilty of a misdemeanour while women who do the same work are guilty of a felony. As a result, female sex workers are often netted in mass arrests by the police and county officers.
On this night, many girls say business is bad. On a street where one does business, sex sells for as much as Sh5,000 per encounter.
The first HIV case in Kenya was reported in 1984. Ten years later, he joined the world of HIV advocacy and activism as a Red Cross a volunteer in Thika.
He admits that some friends have left him because of the nature of his work.
"When you deal with condoms and sex workers, you are not the most popular person. Fortunately, my wife who is a church minister, and my children fully support me," he says.We end the night after 3am near what used to be Simmers Club in a lively conversation with five girls who have been in the streets for a while. They regale us with happy stories of families and friends.
but dark tales of their stints in jail and the things they have had to do to survive. They like to talk and the King of Condoms is a good listener. It is a partnership that works.