Do it in the country they like it just fine, do it in the city it’s a $20 fine,

That stench on your CTA bus? That puddle of urine? Turns out riders aren’t always the ones to blame.

The Chicago Transit Authority has disciplined three bus drivers who were caught relieving themselves on their routes in the past few years, according to CTA records obtained by the Chicago Sun-Times.

In one bizarre, on-duty incident in September, a driver defecated on his bus after pulling over — busted by onboard surveillance camera footage.

The driver told his bosses he couldn’t hold it because he’d eaten “bad tacos.” CTA officials didn’t buy his story, according to a transit source who says the incident appeared to be “premeditated.” The agency initiated termination proceedings.

The source, who works for the CTA, says the official records don’t come close to revealing the extent of the problem, saying it’s fairly common for bus drivers to urinate or otherwise let loose on or near their buses and let the blame, and cleanup, fall to others.

“I can tell you it’s dozens we’re aware of,” the source says, adding that incidents are often ignored by supervisors or “classified as something else” in paperwork to obscure the offense. “This happens frequently, honestly. . . . There’s really no good excuse for it.”