I just got my hair transplant yesterday. I want to have a body massage. Is it Ok?

Considering that you just had your transplant done yesterday I would not recommend having a massage the next day.  The grafts have not yet adhered to the sites in the scalp where they were placed and could easily be dislodged.  It takes at least five days for the hairs to be permanently attached.  Even after this period of time you should be careful doing any vigorous activity as the sites are still healing.  In most cases you may return to any activity you would like two weeks after your transplant was performed.  
Your surgeon may have specific instructions regarding activity after your transplant and it would be best to discuss this with them.  

Dear Brent, 
I would strongly advise against having a body massage so soon. The grafts have not yet anchored properly, so no point taking any chances as you might dislodge the grafts accidentally. In my opinion it is best to wait for a week. Again if in doubt, you should contact your hair transplant surgeon.
All the best

Depending on the extent and areas of transplant, it is possible that grafts could be displaced during positioning and turning.  Given that you are only one day out from surgery, this is a question best answered by your surgeon.