CALL me old school, but I think it’s totally inappropriate when people turn up for a wedding dinner in jeans.

In fact, I think it’s rather slack and rude.

If the happy couple can get gussied up, put themselves through a song and show, and get in at least two changes in outfits, then surely folks can make a little effort and return the favour graciously.

A guy pal tried defending this inappropriate “behaviour”, rationalising it as “a matter of options – none”, according to him.

But this is a friend who practically lives in jeans and tees all year around. For him, dressing up means wearing a polo shirt with black jeans and his best Adidas sneakers.

You know the sort – we all have them in our stable of friends.

And it’s a remarkable contrast to my housemates, both very male, and very finicky about what they wear.

One of them worships in the house of Hermes.

He not only has a briefcase from the French luxury house, he’s got a Birkin bag too and several complementary accessories.

And don’t even get me started on his dress shirts and suits.

My other male housemate outranks me as an indulgent shopper.

Currently we’re racing to see who gets to fill up the wardrobes in our hall, and I dare say, he might be the winner.

The bottom line: There’s very little reason for “no options”.

More likely it’s because most guys are truly clueless at what to buy.

So to take the guesswork out, here are the cue cards for men’s fashion this Spring/Summer 2010:

Buy a grey suit

It’s steely, modern, and really, you’re less likely to be mistaken for a hotel front-desker or worse, security.

Red is a bold colour – use it to your advantage

We especially like Bottega Veneta’s sharp and dapper crimson suits, but if you’re less adventurous, a bright man-bag in the shade can be an alternative.

Get transparent

In keeping with this season’s breakaway from rigidity, you’ll see a lot more layering. As such, designers turn to see-through, lightweight fabrics (think Dior Homme).

Or like at Prada, where perforations were the order of the day.

Flash your toned biceps

They will be on show for Spring as designers did away with sleeves.

Keep the shorts, not bermudas

Yes we know the local men love ’em. But the hemlines do inch upwards (they are most definitely not bermudas or your badminton shorts) to show knees and even some thigh.

Wear it well this season, by pairing off with a boxier jacket. This is how you make casual, chic.