There have been myriad memorable mustaches to grace the diamond, from Dick Allen to Rollie Fingers to Reggie Jackson, but perhaps none is as infamous as the extremely fake one Bobby Valentine slapped above his upper lip one warm June night in 1999.

So maybe the disguise didn’t come together with Mrs. Doubtfire-esque care, but the Mets manager’s dugout hijinks during extra innings of that tense game against the Blue Jays have stood the test of time. The story has become an indelible part of Mets lore, even if it tends to get embellished just a little bit more each time it’s retold. But there are certain facts we do know, from the man himself, about the time Valentine went incognito.

It all started with a pitchout. Valentine called it from the dugout, hoping to prevent speedy Blue Jay Shannon Stewart from sneaking into scoring position in a tie game in the 12th inning. On the surface, it looked like the move would pay off. Stewart bolted for second, Mets catcher Mike Piazza received the pitch from Pat Mahomes, took two lengthy steps in front of the plate and threw down. The throw was not a great one (that often gets lost in this re-telling), and Stewart was safe even with Valentine’s prescient pitchout call, but the umpire deemed Piazza had come too far out of the box and called a catcher’s balk.

That got Valentine fired up, and the skipper stormed out of the dugout to protest. What he couldn’t have known then was that he wouldn’t be returning to the dugout, at least not as the clean-shaven version of Bobby Valentine.

“Now, I have read the rulebook for all my life, but I had never seen nor heard that play being enforced in a game, so I came out to talk with [home-plate umpire] Randy [Marsh],” Valentine told ESPN on the 20th anniversary. “I asked him if I could get thrown out for what I was thinking and he said no. Then I told him what I was thinking and he threw me out.”

Valentine was no stranger to being sent off (he had 17 ejections in his seven seasons in Queens, and in one underwhelming stint with the Red Sox in 2012 he got the boot six times), but this one came at a particularly crucial point in the season. From May 28 to June 5, the Mets had lost eight straight, resulting in an overhaul of Valentine’s coaching staff. Though they’d won three in a row entering this matchup with Toronto, the skipper understood there were some fresh faces on his staff in the dugout and didn’t want to take any chances.

With some egging on from Robin Ventura and Orel Hershiser in the clubhouse, according to the manager’s telling, Valentine revamped his look with a hat and sunglasses, though he was skeptical about the spectacles considering it was a night game. But the piéce de résistance was the two pieces of eye black tape Valentine applied to his upper lip, giving him a Hercule Poirot-style mustache.

“I looked at [Ventura and Hershiser] and they said no one will ever know,” Valentine said.

Well, he was wrong about that part. Cameras in the dugout caught him almost immediately, in part because Hershiser had been enlisted to block the manager but didn’t quite come through. Announcers could be heard laughing at the sight on the broadcast (“That is not Groucho Marx, that would be the manager of the New York Mets.”)

The jig was up. The skipper who thought he was slick had been outsleuthed. When asked about the disguise after, Valentine cheekily tried to deny it: “It was somebody else who didn’t look like me,” he said, according to reports in the New York Times that day. But he has since come to embrace the moment, which became as much a part of his legacy as any World Series appearance (the Mets did make one under his watch). It helped, of course, that his team won that game in the 14th on a Rey Ordonez walk-off single.

Following a two-game suspension and a $5,000 fine for his shenanigans, Valentine returned to the dugout as himself again and the Mets rewarded their manager.

“We needed a little levity. I needed to see the guys smile,” Valentine told MLB Network. “We were laughing together, playing together and we made the playoffs.”

From that game against the Blue Jays through the end of August, the club went 50-25, capturing the NL Wild Card and ultimately falling to the Braves in six games in the NLCS. It’s that summer run that sticks with Valentine, more even than the legendary disguise. That and the minor grudge he still holds against Hershiser for not keeping him hidden.

“I always say, ‘Orel, why didn’t you block out that camera. You owe me five grand,’” Valentine said.