Some people a great liars, inventing stories and concealing truths without the slightest slip-up. Other, unfailingly-transparent people are incapable of fudging a single, mundane detail without getting shifty-eyed. But, there’s a trick, courtesy of recent psychology research, that terrible liars can use to fib like the sneakiest confidence man — and it requires nothing but willingness to endure physical discomfort. Ready for it? Are you sure? Okay: Hold your bladder. That’s right: the best time to lie is when you really have to pee.

In the study, which will soon be in the journal Consciousness and Cognition, psychologists found that people lie more convincingly when they need to pee. The connection between suppressing truth and urination comes down to self-control and, actually, makes a lot of sense.

Here’s why: From passing up nachos to blocking out a scarring experience, a wide array of emotional, cognitive, memory-related and motor challenges force us to practice inhibition. And, while these assorted processes have distinct neural bases, they all involve overlapping brain networks. Previous studies have demonstrated that inhibitory processes individually strain cognition. But, there’s evidence that simultaneously performing two otherwise unrelated inhibitory tasks, according to a theory called Inhibitory Spillover Effect (ISE), makes it easier to do both of them.

Deception, according to the study, is an inhibitory act because liars need to keep track of how they’ve deviated from the truth, think of a believable lie and monitor both their and other people’s behavior. Earlier studies suggest there’s a high “cognitive cost” associated with lying, as they’ve shown that people have slower response times when they’re spinning lies than when telling the truth.

“Researchers figured that people would become better bullshit artists when they had the need to urinate. They were right.”

For fairly obvious reasons, convincing yourself not to pee also requires inhibition. So, in the current study, researchers figured that people would become better bullshit artists when they had the need to urinate. They were right.

Here’s how it went down: researchers recruited 22 college students to fill out questionnaires about views on such social issues as abortion and the death penalty, knowing that they’d later be interviewed about their opinions. Study leaders also asked the students to drink water and, concealing the true purpose of the exercise, told the students they were participating in a water taste-test that was unrelated to the main study. Per instructions, students used the bathroom before tasting water, believing they’d have no other chance to go until the study ended. Researchers then randomly assigned half the students to drink 700ml of water, while the other half only had to drink 50ml. After a 45-minute waiting period, students sat for their video-taped interviews.

Researchers told some students to field interview questions truthfully, and instructed others to lie. The students broke down into four groups: liars and truth-tellers with urgent and less-pressing needs to empty their bladders.

A different group of student volunteers then observed the taped interviews, rating a number of physical and verbal behaviors that, according to previous studies, are relevant to detecting deception.

In a second, similar experiment, researchers showed the same taped interviews to another (third) group of students. Rather than assess behavior, these students only weighed in on whether they thought interviewees were lying or telling the truth.

Across both experiments, students who had to pee more urgently (because they drank more water in the fabricated taste-test) both exhibited fewer behavioral cues associated with deception and more convincingly lied about their opinions than students who’d consumed less water. Those who really had to pee also invented longer, more complex lies, which researchers interpreted as indicative of greater cognitive control.(Interestingly enough, levels of bladder fullness didn’t appear to have the same impact on truth-telling)

So, next time you call in “sick”, do it after a few too many Poland Springs. Worth a shot, anyway.