If you're planning on telling a tall tale, make sure you haven't been to the toilet in a while.
People lie more convincingly if they have a full bladder, according to research by academics at California State University.
Iris Blandón-Gitlin's team asked 22 students to lie to a panel of interviewers. Half were given 700ml to drink before the interview and the other half, just 50ml.
The students with the full bladders showed fewer signs that they were lying and their untrue answers were longer and more detailed, meaning interviewers were less able to detect that they were telling porkies.
This isn't the first research to suggest that bladder control impacts human behaviour.
In 2011 Mirjam Tuk of Imperial College, London found that people with full bladders were better at resisting short-term impulses.
Enoch Powell reportedly had a preference for giving speeches with a full bladder as it helped him focus. It is understood that David Cameron uses the same techniques.
Blandón-Gitlin told New Scientist her study did not suggest Cameron's use of the technique meant he would be more deceitful. However deception might be made easier using the approach.
