There must be moments in Tim Vine's life, I think to myself, where he just wants to be taken seriously.
The problem with being funny all the time is that everybody, or at least strangers like me, thinks he's always joking.
What if, for example, Tim Vine came running up to you in the street and told you there was a house on fire?
Would you believe him? Or would you laugh, a little awkwardly, at some clever wordplay you must have missed?
I make this mistake when I call him on his mobile to talk about his upcoming shows in Kingston, East Molesey and New Malden, where he will be trying out new material ahead of his new Edinburgh Fringe Show, Tim Timinee Tim Timinee Tim Tim To You.
"Call me on my landline," he says. "So I don't have to stand next to the window."
I chuckle, thinking that the fact it's Tim Vine, he must be joking. But then he hangs up. Because he does actually have to stand by the window to get reception on his mobile.
Likewise, he tells me an incredible anecdote about the Fighting Cocks in Kingston, where Vine and other well known comics including Jimmy Carr and his former Not Going Out co-star Lee Mack, regularly appear for the Outside The Box comedy nights.
"Robin Williams did it once," he says. "He was appearing at Prince Charles' birthday and he needed somewhere to try out his material.
"The audience had no idea it was happening. Maff (Brown, comedian and Outside The Box founder) apparently said: "We've got a surprise for you tonight - Robin Williams!" and the audience laughed.
"Then Robin Williams actually walked on! To a room of about 80 people.
"I wasn't there though, sod's law."
Robin Williams will not (we think) be appearing at Outside The Box's mini festival of comedy, which takes place from July 4 to July 28.
But you can still see the likes of Vine, Jupitus and Brown, as well as Mark Watson, Stephen K Amos, Christian O'Connell and Kevin Day appearing in venues across the borough throughout the month.
In the spirit of Outside The Box, all are road testing new material ahead of Edinburgh.
"The title is the only reference to Mary Poppins in my show," says Vine. "Although I might come on stage dressed as a chimney."
Unsurprisingly, tickets to see these top comedians in tiny venues sell out fast.
But at the time of writing, tickets to Vine's gig at the Royal Oak pub in New Malden are still available.
"I was at the Han Bar in New Malden last night," says Vine. "I wanted to do some karaoke, but I had no one else to go with.
"So I went on my own.
"It was great fun - I recommend it. you don't have to wait your next turn, and if it's not going well you just switch it off and do another one."
Again, I chuckle, assuming there's a pun in there somewhere I've missed.
The following day I check out the Robin Williams/Fighting Cocks thing.
Turns out he did play there once - Vine wasn't joking.
Maybe it's time to book a booth at Han Bar...
The full line up for the Outside The Box festival is as follows:
July 4: Barn Theatre, West Molesey: Al Murray and Maff Brown 8pm
July 7: The Fighting Cocks, Kingston: Tim Vine 8pm
July 8: The Royal Oak, New Malden: Kevin Day and Maff Brown 8pm
July 10: Barn Theatre, West Molesey: Tim Vine 8pm
July 14: The Fighting Cocks Pub, Kingston: Phill Jupitus and Matt Forde 8pm
July 17: The Royal Oak, New Malden: Tim Vine 8pm and 9:30pm.
July 21: The Fighting Cocks, Kingston: Danny Bhoy and Ellie Taylor 8pm
July 23: Barn Theatre, West Molesey: Stephen K Amos 8pm
July 24: The Corner House, Surbiton: Mark Watson and Maff Brown 8pm
July 28: The Fighting Cocks, Kingston: Christian O'Connell 8pm
Click here for tickets.