'Tell them what an idiot you are." That was the curt instruction from the woman who edits this column. No political rants this week. Just explain to those who don't already know it that I'm an idiot. Here goes:

Men are idiots. Fact. Scientists proved this last week when they discovered that Man 'Flu actually exists. We exaggerate the symptoms of the common cold to idiotic proportions. We think we're the stronger sex, but we're not.

We're also idiots who can't accept that ageing is inevitable. The Harley Medical Group has reported a 17% rise in calls from men seeking Botox treatment since Louis Walsh admitted getting work done. Presumably hair weave enquiries also rose after Gordon Ramsay had his hairline restored. Men are idiots. Vain idiots.

The worst thing a man can do, next to wearing a wig or getting Botox, is to dye his hair. He is a preening knob if he does. He's cheating. Besides, grey is manly, grey is wise.

Grey is also bloody boring. I've an admission to make: I'm a preening knob. I dyed my hair last weekend. No, please don't turn the page, let me explain.

I've been letting my grey hair grow for the past year. I love taunting my baldy mates by draping it over their shiny heads. Over the past few months, however, it's been turning a horrible shade of green. This is something the Baldies love reminding me about. ("Look, it's the Not-So-Incredible Hulk!")

Sick of hearing me moan about it, my sister bought me a bottle of 'Super Silver Sensations!'. She promised it would sort the greenness out. I lathered half the bottle in, ignoring the instructions to rinse after five minutes. I'll give it 40, I thought. To get it REALLY silvery. An hour later, my hair was purple. 'Silver Sensations!' turns out to be blue-rinse shampoo. My head looked like Barney The Dinosaur's crotch.

"No, you don't look like Barney," my wife reassured me. "You look like old Mrs Slocombe. You idiot."

Shortly afterwards, someone told me ketchup can rectify yellowness. It took 15 minutes to apply because, being a man, I had to mess around, teasing my hair into various shapes. I let it dry into a two-horned, devil 'do'.

The whang was appalling but I soon forgot about my saucy bonce as I caught up on household chores. Two hours later I went into the study to play with the cat. She shied away from me. "That's odd," I thought, reaching out to pet her. She licked my face and hissed again. I looked up to see the postman staring in the window. I waved. He slowly backed out the gate.

My ketchup 'horns' were melting down the side of my face. It looked like I was engaging in some perverted Satanic ritual with the cat. "Come back, I can explain," I called, which only made him run away faster. Ketchup doesn't work, by the way. It turns your hair ginger. My pub-mates started calling me 'Rusty'.

So I bought some Grecian 2000, but that turned my pillow brown, which was hard to explain to our disgusted (former) cleaning lady.

I bought a bottle of Just for Men hair dye, but I couldn't use it. I'm not that vain. I threw it in the bin. It came out again last Saturday in advance of an appearance on RTÉ's Daily Show. "Don't put that in your hair. You'll make a mess of it," my wife warned, forgetting that men are idiots. We'll always press the button marked 'Do Not Press This Button'. We'll always stick a knife in the toaster when it's plugged in.

I emptied the bottle onto my head. 'Two minutes is all it takes!' the label said. I left it in for 10.

My wife says the screams were up to The Exorcist level. My hair was black with red roots. I was a cross between Elvis and Bono. "It's all YOUR fault," I shrieked, as she locked herself in the bedroom with the cat.

I lathered Fairy Liquid into it. I steeped it in lemon juice. It turned grapefruit pink. I shrieked some more.

It took a colourist friend two days to rectify things. It still looks dyed though and I'm paranoid about it. The worst thing is when you catch someone staring at it and quickly looking away.

There's a lesson in this for all you fellow idiots who may be thinking of dyeing: don't do it. I miss my grey hair.

The last straw came when I went for my first post-dye pint. A wag shouted: "You can't come in here … it's Just For Men."

"Manity" means I'm staying in until I go grey again. If anybody asks my wife where I am she's instructed to say I'm at home, under the weather.

Knowing me, they'll probably think it's Man 'Flu.