Im making a toaster cake and i just tried to make gray out of black icing and white fondant it turned blue this cake is due in three hours help!!!!!

I'm not sure if you meant to say icing, but if so, be sure to use Gel Food Coloring, not icing You can get it at Michaels or any cake supply store

Your black food coloring from Wilton (or other gel colors) should make it perfectly.

Any chance you have silver luster dust. I've painted with silver luster dust and lemon extract onto white fondant and it turns out great! The lemon extract is very high in alcohol, so the mix will dry very quickly. I just keep adding drops of lemon and occasionally add more luster.

I'm not sure what you mean by adding black icing to white fondant? Be sure to use black gel color and only add a little at a time. If it has a blue tint, go ahead and add a bit more until it gets the gray color. Most black coloring has a base of blue, but I've never seen it turn fondant blue, only my hands. If you're using black gel coloring, could it be old?? Good luck!