Talking to the BBC, Mr Rowe said he thought his agent was lying about the award.
"He rang me and told me I couldn't tell anyone for a week which has been almost impossible.
"I'm massively taken aback by it. I've never seen myself as being in the running for things like this. It's a massive honour and a genuinely huge surprise."
He said the line came about by accident at a performance when he was quizzing the audience.
"A guy said he worked in the Jobcentre and I said the joke that has now won the award.
"Because it got such a nice reaction on the night I thought I had to do something with it as a line. I didn't expect to be winning an award for what was essentially a brain fart."
Last year's best joke came from student Ken Cheng. "I'm not a fan of the new pound coin, but then again, I hate all change."
FUNNIEST JOKE FINALISTS
These are the runners up in the funniest gag of the year competition.
• Leo Kearse: "I had a job drilling holes for water — it was well boring."
• Olaf Falafel: "I took out a loan to pay for an exorcism. If I don't pay it back, I'm going to get repossessed."
• Daniel Audritt: "In my last relationship, I hated being treated like a piece of meat. She was a vegan and refused to touch me."
• Flo and Joan: "What do colour blind people do when they are told to eat their greens?"
• Darren Walsh: "I've got a new job collecting all the jumpers left in the park at the weekends, but it's not easy. They keep moving the goalposts."
• Justin Moorhouse: "Trump said he'd build a wall but he hasn't even picked up a brick. He's just another middle-aged man failing on a DIY project."
• Adele Cliff: "I lost a friend after we had an argument about the Tardis. I thought it was a little thing, but it seemed much bigger once we got into it."
• Alex Edelman: "Why are they calling it Brexit and not The Great British Break Off?"
• Laura Lexx: "I think love is like central heating. You turn it on before guests arrive and pretend it's like this all the time."