A very small sample of interactions with my son today:
“Mummy? What are you doing?”
“I’m doing my dissertation.”
“Ooooh. Can *I* do your dissertation?”
There are moments when I might seriously consider this offer…
***
“Mummy? Am I being quiet?”
“Well… not exactly…”
“Am I being quiet now?”
“Not really, no…”
“Mummy look! I’m being QUIIIIIIEEEEETTTT NOOOOOW!!!”
***
*coming slowly to my senses out of the dissertation fog, realising that I’ve been hearing strange spitting sounds for some minutes*
*looking down at floor, realising that there are peanuts everywhere*
*while I’m puzzling over this, I hear another spitting sound, and a peanut goes sailing past*
*I look back, and my son has a bowl of them, which have apparently been providing ammunition for a sort of freestyle spittoon event for some minutes before I registered what was going on*
“Uh… do you think you could maybe do that outside? Maybe the birds will like it…”
*a few minutes later*
“Mummy! The birds don’t like it! Can I do it in here again?”
***
*my son pops open a window to my study, from outside the house, and peeks his head in*
“Hey Muuuuuuummmmmyyy… hey Muuuuuummmmyyy…”
etc., etc.
***
Strangely, it hasn’t been a bad day for writing. I’ve been working on a fairly intricate moment of the argument, so I don’t think it would have been particularly quick going, even without interruptions. Admittedly, I hadn’t expected to get an average of five minutes’ concentration time between disruptions… Even so, I’ve just finished the section I was intending to write today, and with some luck might get a bit of a head start on what I had planned for tomorrow. And the creativity and sheer doggedness of the interruptions has kept me laughing all day long.
Rough Theory 
This is great. If you don’t mind my asking, how old is your son?
My wife works as a nanny for two small kids. One of the things she’s worked on with the older (two or 2 1/2 years old) is to ask him when he’s having a tantrum – “do you want to stamp your feet and yell, or do you want to do X?”, to try and reason him out of the tantrum, and also to try not to give in just because he tantrums. One of the funnier effects is that sometimes when he’s upset or when he’s trying to exert power by his behavior is that he’ll narrate what he’s doing or going to do – “I’m going to lay down on the floor any yell!”, “I’m crying!” etc.
He’s three and a half – and he does something a bit like the narrativising tantrums thing as well: when he wants to do something, and the condition of doing it is that he not behave in some way he’s been behaving, we’ll have a conversation: “Now, if we go to the store, you’ll have to do [x]. Do you think you can do that?” And he’ll sometimes go, “No, I don’t think I can do that”. It’s lovely – complete honesty at this age 🙂 (Although we do occasionally have the “imaginary friend thing” going – strangely, he doesn’t blame things he’s done on his imaginary friends: he admits that “he” did something, but claims that the person we’re talking to at the moment isn’t “him”, but one of the various imaginary people he plays with… ;-P It’s great. The imaginary person will talk all about how my son really shouldn’t have done something – it’s hysterical.)