How do you compete with the worldwide tendency for boys to speak 'truck'?

As I write this, my son - the one with the gray plastic knight's helmet and the purple soccer suit - is playing at rescuing his sister, the self-styled baseball-playing princess. This is what comes, you see, of raising children in a nonsexist manner: absolutely nothing.

Oh, we've tried, we've tried. We purchased at least $25 worth of Legos for our daughter, who spent her early years watching Mom and Dad build with them. Occasionally we could get her to pick up one or two bumpy blocks and fit them together. But then, when she got to a more sophisticated age, she gave them to her brother - along with the car models and blocks we'd bought. She kept the dress-ups.

She also kept the dolls, since her brother refused point blank to play with any (he does play with ''Star Wars'' figures - do we get points for that?).

We kept on trying. We bought a build-your-own Washington Monument cardboard kit, and mother and daughter sat down one day to decipher the Tab A/Slot B rules. Ever seen a leaning tower of Washington?

Then there was the suggestion I made to our male offspring that he might like to read to his sweet stuffed animals, ''like a good daddy.'' He shot me one of his ''get real'' looks and said, logically, ''They're only stuffed animals, Mom, they can't really see.''

Maybe it was the example we set. Maybe if I learned to mow the lawn or insisted that my husband do the laundry periodically, we'd have nonsexist children. I have friends who don't do laundry for their husbands. They all have maids, and their children play rescue-the-princess with mine.

Or maybe it was something else - maybe we're dealing with cultural biases so overwhelming that no switching of lawn mowers and laundry will change them. Consider, if you will, this small but significant story:

My son had a friend in preschool who had spent his entire life (up to that point) in refugee camps with other Laotian children, a fact that probably accounted for the little fellow's shyness and complete inability to speak English. After much nagging on my son's part - and several well-intentioned efforts on my part to communicate with the Laotian boy's parents - we arranged for the friend to come home with us one day after school.

I was more than a little curious to see, first of all, how a just-out-of-refugee-camp child would react to being in an American home, and second, on what basis he and my son had formed such a fast friendship. The Laotian reacted to our home as if it were his, plowed silently and quickly through his peanut-butter-and-jelly sandwich, and then turned his wordless attention to my son, who took him out to the sandbox. There they spent the next two hours playing with trucks, saying ''Vrroom! Vrrrooom!'' to each other, and giggling.

So you see, we're up against something heavy here - a worldwide, culturally reinforced male tendency to speak ''truck.'' How can you compete with that?