AFTER Wednesday night, I might never have sex again. Invited to join a team of writers competing in the SEXplained sexual health quiz at the Café Royale in London, I decided to swot up on the subject by studying the associated website, WillyWorries.com.

Yuck. The cartoon artist penises were bad enough, but clicking on them revealed a clutch of grimly hued photographs (the chanchroid range would traumatise the Marquis de Sade) likely to give trainee urologists second thoughts.

However, I have come away from the whole stomach-churning experience with gifts: gifts of knowledge (I now know exactly how many sperm hang out on the end of my penis, and let’s just say it’s rather more than the number of angels on the head of a pin), and gifts for you, the sexually active but responsible reader.

In the heat of the moment, Trojan, America’s No 1 condom brand (whose slogan is not, disappointingly, “One Yank and it’s off”), which is now “Coming at last!” to the UK (and was sponsoring the evening), has offered me a year’s supply of condoms for a lucky reader. Actually, the reader would have to be very lucky indeed: in Trojan Land, a year’s supply is a performance-anxiety-inducing 366 condoms.

If you can match this fire rate, see the quiz at the end for your chance to be among the first to sample Trojan’s new Shared Pleasure, which actually heats up so you don’t have to. (A burning sensation, it seems, might no longer be a symptom of something you picked up at the weekend.) The nibbles dished out in the bar at the event served as an odd barometer of the evening’s success in dishing out sex education to all the so-called grown-ups who turned up to test their knowledge (feeble, as it turned out) of anatomy, infections and contraception. Before the first round, the nuts in bowls on every table were disappearing like seed on a freshly sown lawn in Pigeonville. After the break, by which time we had all been forced to consider the true vileness of the human body, they remained untouched. Not only were we by then wondering where everyone else had been (and whether they had washed their hands), but we had a pretty shrewd idea.

The judges — a GP, gynaecologist and sex educationist — slumped visibly into a slough of despond as the evening wore on and the true extent of the general down-there ignorance became apparent. I don’t know which was more scary: the blank looks on the faces of most of the blokes in response to the question “Where is the cervix?”, or the suggestion of “Four hours!” from the Scare Dem Crew table as the average length of time from penetration to ejaculation.

So how fared the four worldly wordsmiths? Rubbish. I name and shame Jane Wenham-Jones (Raising the Roof), Mil Millington (A Certain Chemistry) and Lou Wener (The Perfect Play). And me, I suppose. We came 18th out of 23, despite sharing a table with a senior nurse and a midwife, who had come along to support Lambeth Nurses (who failed to show, presumably having gone out on the pull instead), and ended up winning the quiz. (Although my faith in their knowledge faltered briefly when one, declining to fill her boots with the free rubbers on offer, muttered “We have condoms coming out of our ears”.) Tuckbox, a company that specialises in delivering champagne and chocolates, came last, which goes to show that just because someone knows how to get into your knickers, it doesn’t mean they know what to do once they have.

And so, for a year’s supply of Trojan’s finest: 1: What is the average time from penetration to ejaculation? (Ignore the Scare Dem Crew.) 2: What is the average speed of sperm leaving the penis? (Clue: it’s legal in a built-up area.) 3: How long does sperm survive in a woman? (Not quite long enough to need a TV licence.)

JONATHAN GORNALL

jonathan.gornall@thetimes.co.uk