[VIDEO] Jay Leno calls NBC brass 'snakes' during 'Tonight Show' monologue

Jay Leno reportedly received a complaint letter from NBC Entertainment Chair Bob Greenblatt when the "Tonight Show" host mocked the Peacock's flagging ratings in a Feb. 28 monologue.

Leno said late night comedians have long been known to make fun of their "masters," and demonstrated his intention to keep doing so with another, even harsher joke on the March 18 episode.

“You know the whole legend of St. Patrick, right? St. Patrick drove all the snakes out of Ireland, and then they came into the United States and became NBC executives."

The burgeoning feud comes as rumors swirl about Leno's departure. The Hollywood Reporter said earlier this month that Jimmy Fallon would succeed the long-time late night host.

"We do not speculate on rumor," Leno's rep said at the time.