Who knew Mr. Met was such a threat?

According to a new book, "Yes It's Not In Here" by AJ Mass, who played the wacky Mets mascot in the 1990s, he was threatened by a secret service agent for getting too close to President Bill Clinton at Shea Stadium.

"We have snipers all around the stadium, just in case something were to happen," the agent told Mass at Shea on April 15, 1997.

"Like I said, do whatever it is you normally do. Nobody will bother you. But approach the president, and we go for the kill shot. Are we clear?"

Mass describes the Secret Service agent saying these words to him as not "only looking into my eyes, but also into my very soul with his blank, unblinking stare."

Clinton was at the stadium to mark the 50th anniversary of Jackie Robinson's debut in the major leagues.

Mass survived, and lived to tell not only that tale, but a slew of other stories about the hidden life of professional mascot-dom.

The book also includes historical context, starting with the royal tradition of court jesters and including not only his experiences as Mr. Met, but the unique and little-known stories of other high-profile mascots. It is on sale now wherever books are sold.