INT. BILLY'S BEDROOM – NIGHT.

I open the door to find Billy lying on the floor, arms at his sides, legs together, toes pointed. There is an intense look of concentration on his face.

ME: Billy, what are you doing?

BILLY: (without hesitation) I'm playing luge.

A beat.

ME: You mean the sled thing that goes down the ice chute?

Another beat.

BILLY: Mama, will you play luge with me?

CUT TO

A few moments later …

Both of us are now lying on the floor, side-by-side, with our toes pointed.

BILLY: Mama! Are you winning?!

Yes. Yes, I am.

There was a time when I despaired that by the time my son was 3 or 4, he would abandon me in favor of his dad. Because he was a boy, I imagined that eventually, sports would start to infect his brain and he would come to pity me and my sad lack of any kind of ball-playing skills.

He turns four this summer, and Billy's ball games are still very inclusive of those with special needs like myself. "Billy Ball Tag," one of the games he invented, involves me throwing a ball in his general direction and missing, so that he can shout, "You missed!" I got serious skills in Billy Ball Tag.

Then there's "It's a fumble!" which requires one of us to pick up the football (an American football for those of you Brits who still insist on calling the round black-and-white one by the wrong name), running to the other side of the yard and screaming either, "Touchdown!" or dropping it and yelling, "It's a fumble!" When we fumble, we also have to fall to the ground and pretend to cry. It turns out that Billy's understanding of the rules of football are pretty much on par with my own.

Floortime therapy has taught us to follow Billy's lead when it comes to play. He has better ideas for games than anything put out by Parker Brothers. After he gets comfortable with playing a simple game, we try to add a little complication to it that will encourage his desire to communicate.

Dave is really good at this. He invented "Yummy and Yucky" bubbles. Billy dearly loves to have one of us blow bubbles. I've practically hyperventilated trying to keep up with his bubble jones some afternoons. One day, Dave watched Billy pretending to eat the bubbles. He copied him and Billy laughed. So they spent several minutes trying to catch bubbles in their mouths.

Then he started asking Billy, "Is it a yummy bubble or a yucky bubble?" And after Dave "ate" one and declared it "Mmm-mmm, YUMMY!" Billy tasted one, made a face, and said, "Yucky!" and a game was born. Eventually, another layer was added, as we declared bubbles "hot" or "cold," "scary" or "funny," and so on. Beware Billy if he gets hold of an "angry" bubble; he's like the Incredible Hulk.

Sometimes, when we add a complication to a game -- or a "playful obstruction," as Dr. Stanley Greenspan calls it -- we lose him. He just turns his back and moves on to something else. That's the sign that he's not ready to move up the communication ladder any further that day. Or it could just be a sign that our game isn't fun.

Case in point: "Three Little Pigs." Billy loves to act out certain parts of the fairy tale. He likes the part where he hides in his playhouse and I pretend to the wolf banging on the door. He likes the part where he escapes out the window and the wolf has to run after him. He likes the part where the pig jumps into the swing and flies to the moon to get away (a plot twist Billy added to the story). He does not like any attempt on my part to get him to sit down at the picnic table and do a craft in which we build a stick, straw and brick house.

"Stinky Broadfoot," however, is a game that gets more complicated every morning. It started when he climbed into my bed one morning and I told him that he needed to go to the potty with Daddy first and then he could get into "Mama's bed," as he calls it (I'm not sure he knows that Dave also sleeps in that bed). When he resisted, we explained that if he didn't get a new Pull-up, people would call him "Stinky" when he got to school.

Well, there is nothing in this world funnier to Billy than bad smells. He decided his name was "Stinky" and we all three rolled around the bed making faces and complaining about the smell. The next day, Dave adopted the name "Smelly Daddy" and I was "Malodorous Mama." And every day we have to come up with new names for "stinky." Billy has even developed some sort of dance where he holds his nose and waves his other hand back-and-forth in the air around him. God forbid any child at school should ever have some unfortunate gas incident. My child cannot be counted on for any sense of discretion where stink is involved.

As we were rolling around on my bed this morning, contorting ourselves with fits of laughter, I thought to myself that if this is therapy, it sure beats those months when we had him on the gluten-free diet and I spent all my time cooking. Now I can concentrate on developing my skills in "Billy Ball Tag." I'm our team's starting forward this season.