Jerry O'Connell Documents 18-Inning World Series Experience, Back For Game 4!

12:06 PM PT -- Jerry O'Connell joined Harvey and Charles on "TMZ Live" just a few minutes ago ... and cleared the air on his bathroom emergency claim.

JOC said he wasn't really clenching his cheeks during extra innings ... but just wanted to have a laugh with a troll online.

It wouldn't be too surprising if he was telling the truth -- Jerry told us he had seven Dodger dogs, four bags of peanuts and countless beers throughout the 18-inning affair.

But the experience wasn't enough to get him to stay home for Game 4 -- he said he'll be back at the stadium Tuesday night to check out Shohei Ohtani on the mound ... but his seats are even worse!!

Folks got two World Series games in one as the Dodgers needed 18 innings to beat the Blue Jays ... but Jerry O'Connell wasn't gonna miss a single moment of action -- even though he REALLY had to take a dump.

The actor documented his entire Monday night at the ballpark on his social media page ... initially smiling from ear-to-ear as he made his way to Game 3 of the Fall Classic.

JOC was all-in on the experience ... even playfully jawing at visiting Jays fans in the crowd early in the contest.

Little did he know, the "Kangaroo Jack" star -- who is married to supermodel and actress Rebecca Romijn -- was in for a LONG night ... and his pep started to sputter as the game went into extras.

O'Connell made it clear he was going to remain seated, though ... doing his best 'Wolf of Wall Street' impression and proclaiming he wasn't "f***ing leaving."

When one follower tried to downplay his loyalty, JOC explained he was sacrificing a lot more than sleep.

"Bro. I've been here since 4 and I have to s***," he said.

In the 17th(!!!) inning, JOC took a selfie video to make it clear he was going to "outlast [Jason] Bateman" ... who toughed it out, but certainly looked worse for wear in his seats closer to the field.

It was such a daunting night, O'Connell even showed how one fan opted to tune in to a police chase on his phone to get through it.

Thankfully for Jerry's sanity, it was all worth it ... as Freddie Freeman put an end to the madness with a walk-off homer to centerfield in the bottom of the 18th to give L.A. a 2-1 lead in the series.

O'Connell got footage of the highlight and his reaction ... celebrating both the dinger and the fact he could finally go home and, we're assuming, handle his business.