Jay Leno can only be a company man for so long.

Leno, weeks after a terse e-mail from NBC entertainment chief Robert Greenblatt led to rumors he’s going to be replaced by Jimmy Fallon next year, fired off a joke at the expense of Peacock network executives in his monologue on Monday’s program.

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“You know the whole legend of St. Patrick, right?” Leno said. “St. Patrick drove all the snakes out of Ireland — and then they came to the United States and became NBC executives.

“It’s a fascinating story!”

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The tension between the usually affable host and the network exec came after Leno’s monologue on February 28 mocked the network’s embarrassing fifth-place during the most recent sweeps period.

“It’s so bad, The Biggest Loser isn’t just a TV show anymore — it’s our new motto,” Leno joked, which led to an acrimonious exchange of e-mails between he and Greenblatt.

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As we previously reported, Leno’s arch-rival Howard Stern was named as a candidate to take over Fallon’s time slot should the switch of late night hosts occur, but as history has shown — just ask David Letterman or Conan O’Brien — Leno always finds a way to stay in the chair.