Apparently, needing to pee REALLY badly will actually enhance your ability to make a clear headed decision. You would probably think it would impair your decision-making abilities as you would be diverting your time to the fact that you could very well have an accident in front of your co-workers, however, controlling your bladder will help you control all other impulses at the time. This will lead you to make the best decision in any situation.
In order to test this, researchers had people drink a ton of water and then go through different tasks. One of the tasks was called the Stoop task in which participants had to read the name of a color (i.e. green) in a different color ink (i.e. blue). They then were asked to name what the color written was. The normal impulse is to say the color it is written in. Those who had drank the water beforehand were better at inhibiting this impulse and saying the right color. The other task was a series of questions asking participants whether they wanted to accept 16 euros the next day or 30 euros in 35 days. As you may now guess, those who needed to pee more often than not chose to go for the 35 euros in 30 days even though the go-to, impulse driven response is to get cash ASAP.
The researchers also tested people primed to go to the bathroom. After drinking the water and before each task, the researchers primed them by having them complete word puzzles with words like 'urination,' 'toilet,' and 'bladder.' They found that these participants were even better at controlling their impulses than those who had only drank the ton of water.
So now, although it may sound strange... have a refreshing glass of water before having to make a big decision! (I wouldn't advise running out of the room when he asks "Will you marry me?" to grab a glass of water, but you get the point). Good luck!