Caught myself doing the dad laugh at the grocery store
Was in the produce section and my 6 year old said the bananas were all curvy. I literally said 'well they're bananas, not straight-nas' and laughed so hard I snorted. My wife just kept walking. The cashier gave me a look. No regrets.
I've done this exact thing. Kid says something and the laugh just comes out before your brain catches up. Public or not doesn't matter.