Tim Key: I've had a falling out with my friend. It's because of the fruit, you see

(Ping Zhu)

Last night I had a pretty big row with my friend after he defaced some food I'd ordered in good faith from a pizza establishment in north-west London.

I could see the point he was making, of course, but I disliked the way he made it and ultimately I pushed him in the chest so that he fell backwards into a mirror, and I slung about a third of a pint of Dutch lager on to him because I felt he'd crossed a boundary and needed to be told.

The trigger, as it often is with this man, was a difference of opinion about Hawaiians. Not the people – we're both huge, huge fans of Hawaiian people. No, it's Hawaiian pizzas we disagree on. And in particular, the contentious issue of the pineapple. We have opposing views as to whether the sweet, sweet flesh of the pineapple has any business being scattered across the savoury, savoury surface of the pizza. And last night, in a bid to teach me a lesson, he tampered with my order on the way back from Rustica's.

LF has never liked anything to do with Hawaiian pizzas. I've never seen him sadder than when he's staring at some chunks of pineapple sinking into my melted cheese. He can barely look at it. He'll sit there angrily and he'll call it a travesty of justice and he'll shake his head at me. My standpoint is that I'm all for it. Deep down, I know it has no business being there, of course. Pineapple shouldn't be perching on pizza any more than KitKats should be crumbled on to lasagne. But still, I'll take it on. And knowing that LF hates it so much gives me even more of a thirst for it.

"Why don't you chop an apple up, throw that on, too?" is the sort of thing LF will say. "Shall we see if they've got any raspberries?" I simply fold my Hawaiian slices into my mouth. Sometimes I wink at him.

He always lists fruits. That's how it goes these days. Him: listing fruits. Me: eating and winking. "Get some cherries on it, mate." Sometimes he gets so riled he takes his Diavolo into another room. But last night he didn't. Last night he stayed right there. Watched me open my box. Grinning.

Of course, when I'm not with LF I barely ever eat Hawaiians. It's just become a nice way to wind him up. I'm not sure I particularly enjoy having the pineapple on there, but I'll take the hit; often I'll ask for extra pineapple to goad him. I once ordered a Hawaiian to be delivered to a dinner party he threw. Five goons sat there eating some kind of tagine his girlfriend had cooked up; me folding in my Hawaiian; him giving me daggers. Furious.

When I opened my box last night, I was initially stunned. Like Brad Pitt in Seven, I hadn't prepared myself mentally for what I was going to see, so like Pitt in Seven, I was wrong-footed by what was in there.

In a way I admire LF for his ingenuity. The great pineapple debate has been going on for years – maybe we had to move it forward in some way. Well, he certainly had done that. He'd moved it forward by taking a knife out with him when he collected the pizzas. And he'd moved it forward some more by stopping in Costcutter on the way back. And now here, in my box, he had made his point.

A Hawaiian, sure. But barely discernable under a dozen or more plump, glistening slices of banana. I stared down at them. At the point he'd been making for years, now writ large on my pizza. I nodded. I looked up at his plump, glistening face. And then back down at my dinner. He had satirised my pizza.

I placed the box down.

"I thought you liked fruit on it, mate." I began to pick off some bits of fruit and leave other bits on. And I began to question everything I stood for. And then, like Pitt in Seven, I lost it.