I was at a club in San Francisco in 1993 and Robin Williams dropped in to do some improv. He just grabbed all the comics in the room and made us go up on stage with him. I had no intention of trying to compete with him but he just ran circles around everybody. He was trying to get us to keep up with him. I think I played a banana. I can’t remember why. Perhaps because I was tall and had a yellow shirt on. And he was probably a gorilla because he liked playing gorillas.

At that point I’d just auditioned for Mrs Doubtfire and the club owner told me to tell Robin about that. So I did. Robin said: “Well, that shouldn’t be a problem.” And a few days later I got the part. He hired a lot of local comedians for that film. It was great for all of us. I spent a week on Mrs Doubtfire and I never knew when the cameras were rolling. Robin would just start and I’d be like, “Are we filming this? Is this in the movie?” He’d do the scenes as scripted and then toss the script away and try 1,000 other things.

He wanted to do a Barbra Streisand song but he didn’t know any of her lyrics. So Harvey Fierstein and I taught him the lyrics to Don’t Rain On My Parade. Then later we got hold of three huge blonde Ivana Trump wigs and we sang Barbra Streisand to the camera. There was never a feeling that you couldn’t be funnier than him, which is what some leading men are like. He gave Harvey and me so many moments on screen. His generosity was intense.

I didn’t know who Chris Columbus was before we started making the film. I asked him who he was. He said he was the director. I said: “You’re 12!” I was watching him and Robin laughing together for a few days. I thought he was Robin’s acting coach or something. I think he realised that you just need to let Robin go – otherwise you’d miss so much great stuff. Everybody on the set was joking and playful. There was so much comedy going on all the time that I thought it wouldn’t work – I thought, “I’m in a bomb. Where are the gags? Where are the punchlines?” But when I saw it in the cinema I just cried – it was so funny and touching.

I saw him last summer and he looked like an elf – he was just dancing around the stage and enjoying it so much. It felt like he was going to jump in your lap and talk to you. I think he found performing restorative. For some comics, the performance wipes them out but Robin always seemed to have more energy afterwards.

He once told me that he was embarrassed on stage 70% of the time. He said that because he tried so much new stuff, and just said whatever was on his mind, he was embarrassed by it because it was so fresh. I found that really inspiring. He had you on the edge of your seat – in the cinema, yes, but especially on stage. You had no idea what would happen next. The whole place could just flip upside down. And that’s how it should be: the audience should never know, the audience should always be surprised.