Tim Key: Last Sunday, I spent the afternoon trying to get my hands on a pig's heart

(Ping Zhu)

It was a muggy day, I wore a leather jacket that melted in the September sun, and after a couple of hours of plodding, I was on my knees. Hot, heartless and crawling in the direction of Morrisons, my quest was breaking me.

As a rule, I like to have a goal. If I don't have a project to do on a given day I find myself feeling rudderless. I meander about the place, moving in and out of Prets, or banging my head against my laptop. I need to have goals. Booking some seats somewhere, taking back a cardigan, varnishing a mug – something I can sink my teeth into. And so when I was tasked with finding a pig's heart, I was buoyant. But anyone who's ever gone after a piece of offal that specific will understand that there's a fine line between an interesting project and a burden.

The main thing you notice, when you're after a pig's heart, is that asking "Do you have a pig's heart?" feels rude. It sounds like an insult. Even to battle-weary butchers. That's why I spent 15 minutes in the shop before I popped the question. Delivering the line cold might seem menacing; I wanted to establish myself; set myself up as a normal kind of a guy. I also used the 15 minutes to try to find the heart for myself. If I could locate a vacuum-packed one on a shelf then I could just throw the guy some money and leg it – no questions asked. But I never found one, so questions were asked. Such as:

"Do you have a pig's heart?"

"What?"

"Do you have a pig's heart?"

"Why do you want a pig's heart?"

"Why do you want a pig's heart?" sounds like a reasonable question. It was the way they were saying it, though. With their aggressive tone, they seemed to be suggesting I wanted to eat the heart raw, or sleep with it. In fact, the answer was that I needed it for a short film I was making with my friend Jelson. In order to subsidise the money I make from my column, I sometimes work as an amateur filmmaker. In our film, an awkward man hiccups up his heart, so obviously we needed a heart for him to hiccup up. But I never told the butchers this. I liked to keep them guessing.

"Why do you want a pig's heart?"

"Just tell me if you've got one, Mr".

About eight butchers in, I found one who didn't assume I was a pervert. He could see I'd sweated through my jacket and took pity on me. He suggested I go to Morrisons. Morrisons, he assured me, sold pigs' hearts.

I had almost no energy left as I dragged myself into Morrisons. I was surprised to be there, too. I knew they did things like Frosties and ham, but hearts? I didn't remember it from the adverts. Ant and Dec always focused on things like pies, veg and treats. Was it possible that Morrisons did sell pigs' hearts but didn't want to feature them on their ads? Either way, I dragged myself to the offal aisle and hauled myself to my feet.

And there it was. A pig's heart.

Diced.

It was a devastating blow. Morrisons had what I was looking for. It was in my hands. But it was diced. THEY HAD DICED THE HEART. I fell back against the kidneys, clutching the heart cubes. I was all over the place.

I wasn't thinking straight as I plodded, zombie-like, to Morrisons' hardware zone. I was a mess. I picked up Super Glue and staggered to the till.

I had achieved my objective, but I now had a new one. I would spend the evening gluing the pig's heart back together. All amateur filmmakers must have done that at some stage. It was a rite of passage.

I paid up. I had what I came for. I tried to relish the prospect of heart-gluing. I had broken the back of my goal, at least.