Then a server in a light-up Santa cap stood on our table and sang, along with his colleagues, “Froggy, froggy birthday. Na-na-na-na-na. This is how we do it. Na-na-na-na-na.” (Another verse is sometimes added when it’s time to eat the cake: “Put it in your mouth, put it in your mouth.”)

What happened next was captured in a fast-moving video that, like the Zapruder film, I have watched dozens of times. There is a piece of paper on a stick planted in a birthday cake. Then it is on fire. The birthday boy tries to blow it out. He fails. A powerful wind comes out of nowhere. It raises sparks from the fire. The birthday boy’s balloon hat starts to tremble, then shoots straight up in the air like an Apollo rocket. It hits the ceiling. Chaos reigns.

Many thoughts went through my head at that moment. I wondered, briefly, why anyone trusted me with an expense account. But the dominant idea was: Señor Frog’s, where have you been all my life?

I came to Señor Frog’s later than most of its customers. Founded in Mexico in 1969, the chain thrives in Caribbean beach towns and caters to college students on spring break who will fake orgasms on stage to win a margarita. I wasn’t one of them. My most memorable spring break was whiled away in my room reading “The Sorrows of Young Werther” in German.

This did not get me invited to many orgasm contests, but I was inclined to think the time with Goethe had been well spent until Señor Frog’s opened on 42nd Street last summer. For the first time, I wished I had some memories of the chain. So when I ate there, I brought people who had gone to Señor Frog’s in their wilder years. Unfortunately, none of them recalled anything about it, either. One volunteered that he had climbed onto a giant speaker at the Cancún branch and danced furiously, a fact he knows only because witnesses later told him about it.