Jay Leno Calls NBC Execs 'Snakes' in 'Tonight Show' Monologue (Video)

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Jay Leno

Jay Leno isn't backing off the NBC jokes, despite a recent report that entertainment chief Robert Greenblatt is upset over his recent jabs at the network.

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"You know the whole legend of St. Patrick, right?" Leno said in his monologue on Monday night's The Tonight Show. "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."

REPORT: Jay Leno Angers NBC's Robert Greenblatt With Ratings Jabs

Leno and his fellow late-night hosts, including David Letterman and Jimmy Kimmel, have a long tradition of ribbing their networks. But, according to a recent report in The New York Times,Greenblatt fired off an email to Leno after a Feb. 28 episode in which the late-night host skewered the network's falling to fifth place during sweeps month.

During the episode's opening monologue, Leno joked about NBC’s fifth-place status: "We are behind the Spanish-language network Univision -- or, as we call it here in Los Angeles, Cinco de Ratings." Other jokes included: "It’s so bad, The Biggest Loser isn’t just a TV show anymore; it’s our new motto" and "It’s so bad, NBC called Manti Te’o and asked him to bring in some imaginary viewers."

ANALYSIS: Why NBC Should Be Planning Jay Leno's Exit

The exchange between Greenblatt and Leno is said to have occurred before The Hollywood Reporter reported March 1 that NBC was discussing an exit plan for Leno, which would see him cede his 11:35 p.m. timeslot in 2014, likely to be replaced by Jimmy Fallon. NBC has denied the report, but two high-level industry sources told THR the network was considering making an announcement in May.