I've read before that if you are expecting company to take them out to potty before the company arrives.
I can't help you with my own experience, but I found this and I hope you get some help somewhere:
Excitement urination
Some puppies can not control urination when they are very excited. They just get so worked up that they leak urine. Most puppies will outgrow this problem, too (at least based on the ones we see). Some dogs don't, though. We have some success treating these dogs with phenylpropanolamine. It seems to give them just enough control to get them through the excitement. It doesn't always work, though. I have never tried any other therapy for this condition. I think this is because I practice in a rural area and it is easy for my clients to adjust to making these dogs "outside dogs" and living with the problem. If there is an animal behaviorist in your area, your vet may be able to refer you to him or her for help with this problem.
Mike Richards, DVM
Submissive Urination
Puppies that have very submissive personalities tend to urinate small amounts when greeting people or when someone makes sudden movements or assumes a dominant position, even inadvertently. These puppies are generally showing other submissive signs, such as head down postures or rolling over. It can help to just ignore these puppies at first and let them get used to your presence in the house prior to greeting them. Many dogs will outgrow this behavior but some do not. For some dogs, treatment with anti-anxiety medications or phenylpropanolamine can be helpful. Unfortunately, not all dogs will respond to medical therapy or behavioral therapy for this condition. Strategically placed throw rugs or plastic runners are the next line of defense since the behavior often occurs at predictable times and places.
Mike Richards, DVM
http://www.vetinfo4dogs.com/dogbaby....nt%20urination