Andy Richardson: I was reeled in by night of thrilling chat

"Well, I say I'm a virgin. I've had cod, does that count?"

'Mensa', as I call her, makes Jade Goody look smart. Yet, behind the ditziness lies a brain like a snare. That's what you get when you hang out with girlie girl psychoanalysts on a Saturday night. Cuckoo and brainbox, all in the same breath. She rocks. I'm thinking of asking her out more often. It's the best night I've had since my second wedding. And that was a hoot.

Mensa read the menu. Scallops, sole, rabbit. "A rabbit's not a fish," she said, with the gravity of a judge handing down a sentence. There was no hint of irony. There are times when there are no words. 'A rabbit's not a fish'. My mouth fell open. I think I might have dribbled.

"Look," she said, leaning towards me conspiratorially, as though she were about to say something really, really important, like: 'You're the father of my baby, I'm sorry. I didn't tell you. His name's Brian. He has your nose. You'd like him.'

She placed a strategic hand on my trembling knee. I quivered. "If I don't like it, I can always pop next door."

I had no idea what she was going to do next. It excited me. And I wondered why she might pop next door. What was there? A meat shack? A man with a bag of broad beans? A special Doctor Who Tardis through which she could teleport into a less sophisticated world.

"There's a chip shop," she said.

Ah yes, she could have fish and chips, instead of, umm, fish. So that's alright, then. Thank God for Mensa. I had no idea what she would say next. We were on the edge.

Mensa had 'friendzoned' me before we'd arrived at the restaurant. And I was happy that she had. For it gave us licence to say whatever the hell we liked. She spoke to me like one of her bezzie mates, which made for a fantastic evening: who knew girls talked about that stuff? I needed a dictionary and a lie down after she'd finished with me. And I'm still trying to work out if some of the things she said are actually possible. Surely you'd need a mirror and a sling to do that. And do you get a certificate, once you've finished?

We were talking about relationships. I liked to think of it as being a tutorial, rather than a discussion, for romance and I are like North Korea and Ireland. We are aware of each other's existence but trying to find a common bond is like searching for gold in a can of Lyle's Golden Syrup. There is no gold in golden syrup. It's a stupid joke. To think of the time I've wasted searching for precious metal in the bottom of those green cans.

I told Mensa there was no 'I' in romance. She thought I was making a spelling joke. I tried to explain. But she was already onto the next topic: sex.

She told me how she'd decided to go steady with a chap, to avoid him thinking her too forward. Then she'd zoomed into overdrive when she'd realised that he was also going steady. She didn't want him to think that she was thinking . . . At that point, I got confused. I'll never understand the rules of romance. Nor the games people play. Mensa took me under her wing, like Big Bird in Sesame Street. By the end of the evening, I was rapt, sitting quietly, face agog, hanging on her every word.

The waitress brought our fish. 'Oh look,' she said. 'It's sover dole,' as a Dover sole was placed before her. I dribbled for a second time.

Mensa is my favourite person in the world. She's certainly the funniest. And I've already written to her to ask if she'll join me for dinner again. I'd like to take her to another fish restaurant. Or maybe I'll take her to a rabbit farm. Who can tell? I only hope she talks to me with the abandon that she showed before. And I'll probably dribble and wonder what's coming next, particularly if she touches my knee.

She taught me things I didn't know, like the erotic qualities of conversation. "That's where it's at," she said. What: so people like to talk, as well as look? If only I'd known. And in return, I taught her that a rabbit is not a fish.