Im zusammenhängenden Text:
...the boat took us to a small beach where we could swim. "Don't worry," our guide said, "it's too hot for the crocodiles." We looked at him and weren't sure what to do. "Just kidding," he said. so we jumped into the water. It was great.

Wie kann ich das "just kidding" übersetzen? Vielleicht: im Ernst oder kein Spaß?