Can excessive laughing ruin the results of a rhinoplasty?

While it's unlikely that this will negatively impact your results, I recommend following up with your surgeon about your concerns. Your nose and surrounding areas are going to be swollen for a while and you should be consulting the surgeon that performed the procedure. It can take up to a year for final results.
Sincerely,
Philip J. Miller, MD, FACS Double Board Certified Facial Plastic Surgeon

After rhinoplasty, patients frequently realize how much the nose and surrounding tissues move when we smile and laugh.  While laughter is usually great medicine, I would suggest dialing it back a little bit.  It is very unlikely that you will compromise your result, but all the movement of the surrounding tissue could potentially increase swelling, or delay the resolution of swelling.  It is understandable that you are going to smile and laugh, but try to keep it to a minimum, particularly if you are feeling pain or soreness of the nose.    

Hey there and thank you for your interest. 
The only indications, when excessively laughing might have a negative impact on the outcome are, when you had a simultaneous lip lift performed, your lip muscle (Orbiculares oris muscle) was reattached to the alar sill, or your nasal base was narrowed  by resection of thin pieces of skin out of the alar sill area. 
If you want to be safe, I advise you to call the surgeons office and ask, if any steps of your surgery would make laughing an issue.

good luck and keep smiling;)