I'm going to have to go with the infamous "Marty Brown Throws Bases" incident here.
I figured this one will take way more than 100 characters to adequately explain. It's hard to believe it was almost 10 years ago now (on my birthday no less) May 7, 2006. It was a month or two into Marty Brown's first season managing in Japan.
The Dragons were playing at the old Hiroshima Municipal Stadium (a stadium I would visit later that year and also see the Dragons). Domingo Guzman was pitching for the Dragons, and Mike Romano for the Carp. In the top of the third inning, with the score tied 0-0 and one out, Guzman (bizarrely) was on first base having gotten an infield hit. Masahiro Araki grounded to shortstop Eishin Soyogi, who threw to Akihiro Higashide at second for the easy out on Guzman. Higashide then threw the ball to Kenta Kurihara at first. It was a really close play and the umpire called Araki safe.
Romano wasn't too happy about the call and said that it was a "fucked call" or something to that effect. First base umpire Manabe didn't hear exactly what Romano said but just the syllable "fuck" was enough for him to eject Romano from the game. Romano, naturally, was kind of pissed off about this and started yelling at the ump.
Marty Brown came out then to talk to the ump himself, or more like, to first announce Koji Hiroike for the pitching change, and THEN to tell the ump where to shove that call. There wasn't a brawl or anything like that, but the entire team came out while Brown was yelling at the ump.
Eventually, after getting nowhere with the umpires, Brown ran over to first base, pried the base itself out of the ground, and threw it halfway into right field, to thunderous applause from the crowd, indifference from Araki and Kurihara, synchronized "EJECTED" hand-waves from the umpires, and the amusement of just about anyone else watching. He bowed, Japanese-style, as he was exiting the field. Nobody in Japan had ever seen anything quite so crazy before.
Araki and Kurihara went to retrieve the base. The fans kept cheering. The umpires announced that Romano and Brown were both ejected for poor behavior, that Jeff Livesey (bench coach) would be the manager for the rest of the game, and that Hiroike was pitching.
Years later when talking about his interpreter at the time -- Joe Furukawa, who had played for the Carp for a few years, interpreted for Brown, and then eventually got a job scouting with the Texas Rangers and spent a year interpreting for Yu Darvish -- he recounted it slightly differently:
"The first time I was ejected from a game, I didn't know the rules and Joe didn't either," Brown said. "You have a certain time to argue and then the umpires would walk away and you would go back to the dugout. We didn't know that and I couldn't get the umpire to talk to me. The only way I could figure out how to get thrown out was to throw the base to right field. And all four umpires threw me out."For the record, by the way, the Carp went on to win the game, 5-2.
Brown and Romano were both slapped with fines from the league later that week.
But the funny thing is, the Hiroshima Carp team itself was surprisingly supportive of Brown. They even made T-shirts commemorating the event, that said "DANGER" on the front, and "MY MANAGER THROWS BASES" on the back, for the players/staff to wear, and "I THROW BASES" for Brown himself.
There are still a few articles out there about it with photos, like this one from Asahi, or this one about auctioning off the shirts to benefit a musical:
Or you can just do a web image search yourself on ベース投げTシャツ and find quite a few.
I think that's what was the funniest thing about it -- not that the entire episode itself wasn't so funny -- but the reaction of the fans, AND the legacy it created for the rest of that year. Brown also had a few other amusing incidents of getting ejected which also resulted in silly t-shirts being created. This, for example, is a shirt I saw a guy wearing when I was in Hiroshima later that year:
In the end, Brown was ejected a record 12 times over his 5 years spent managing in Japan (four with Hiroshima, one with Rakuten). But honestly, his ejections shouldn't speak for what he accomplished there. Much like Bobby Valentine, though in a more subtle way, Brown helped develop young players and to introduce a new style of baseball in Hiroshima. The time he was there saw the city build a new MLB-quality ballpark, and a year or two after he left the team made it into the playoffs, no small feat when you're a perennial low-budget team competing with the Giants and Tigers. For a while after Brown left I even heard some of my Japanese friends who like the Carp say that Kenjiro Nomura was an idiot and everyone would rather have Brown there, at least he kept things interesting.
BTW, I did consider some other pretty funny things I've witnessed along the way, and my runner-up for this category was the time Tsuyoshi Shinjo thought he should pitch an entire ceremonial first at-bat to Hichori Morimoto (video here - note how his uniform number is actually his face?) but that wasn't really during a game so I figured it didn't count.