How safe is it to take 15000 units of Vitamin d and over the counter supplement?

How "safe" - I have no idea...but it is possible to overdose on vitamins....and well, my Multivitamin contains 400 I.U. of Vitamin D - which amounts to 100% Daily Value....so I think 15 THOUSAND units would be considered unsafe. Wikipedia may contain more helpful information, http://en.wikipedia.org/wiki/Vitamin_D#Overdose