AA,

My girlfriend says she'd like me to be more assertive in bed. So, I said, tell me what you want and I'll do my best. She just rolled her eyes and muttered, "Typical".

 - Norman, Cheltenham

Norman, we've had a number of letters along this line: "My partner says she wants to feel she's being rogered, not directing an interior decorator"; "I've done my best to be a caring sympathetic and sensitive lover but my wife has just told me she's bored to tears with my bedroom good manners and relentless consideration. She'd like me to be a bit more selfish and demanding. Do you think she needs to see a counsellor? Yours, Giles."

All of you: sex isn't fair. It's never going to be fair. It's not an equal opportunity. It's not even explicable. Sometimes, though, it seems that God or Darwin – whichever came first – hardwired the wrong sort of instructions into the wrong bodies.

Men would be much happier if girls behaved like men and women would prefer it if men were as imaginative as women. There is a problem. It's boredom. Women get bored with sex far quicker than men. In fact, no man has ever become bored with sex. We like familiarity, we perform better when there's no anxiety, no unforeseen distractions. Women on the other hand, well on both hands actually, think that familiarity is overfamiliar, that comfort is overrated. They need excitement and surprises and suspense. Sex is like shoes. Men like their shoes to be comfortable. Women like their shoes to be new. You see the problem here.

When she said she wanted you to be more dominant, what she meant is: do something out of character, don't ask my permission, stop pussyfooting, stop saying please and thank you. Now, a sex expert would say – by the way, no one is a sex expert, anyone who tells you they're a sex expert is compensating for being a lousy shag, can you imagine hopping on board a self-defined sex expert? – anyway, what they would say is: role play. It's what they say about everything. It's the easiest way to make over your sex life: pretend it's someone else's sex life. You be the burglar, I'll be the quadriplegic in the wheelchair with the head wand and the number of the safe. You be Helen of Troy, I'll be the wooden horse. You be Jar Jar Binks, I'll be Margaret Thatcher. The possibilities are endless: a sort of hideous, karaoke, trick-or-treat sex life. 

I don't know about you, but I find being myself with no clothes on quite difficult, so having to be Genghis Khan or a Dambuster would be too hideously, shrivellingly humiliating. There is another option: rope and gaffer tape. Bondage and sadomasochism are quite complicated (don't try them when not at home). There's an awful lot of knots to remember. Quite a bit of engineering to take into account. And you've got to constantly be aware that it's still sex, not hostage negotiation or cookery. You need to be very confident for sadism. You've got to keep the atmosphere electric. One wrong move, one slipknot, one Velcro cuff on the pubic hair and it can all descend into Norman Wisdom chaos.

But there is a third way. If I was going to write a sex manual, it would be only one page with one word. And that word would be: blindfold. Dangerous and erotic without ever needing to put on a funny hat or an accent, a blindfold does it all for you. Immediately, it makes you dominant, adds suspense, excitement and a heightened sensitivity. A blindfold is the most versatile and effective sex aid and, best of all, it makes you disappear. There's hours and hours of gibbering, panting fun to be had with a scarf and a clothes peg.

Dear Uncle,

Me and the boys in the dorm have been arguing. What's the biggest penis in the world? Coren thinks it might be his.

Love, Francis

Dear Francis, the largest measured penis was eight feet long. It belonged to a blue whale.