Easy way to get crayon out of grout?
ALL of the grout? If so, I'd say scraping and re-grouting would likely be easiest solution.

If it's just in a few spots, you could try the brown paper bag + iron technique: cover the area with a layer or two of brown paper bag and then apply a hot iron to it. The heat of the iron will melt the wax and the paper bag will then wick it up. Try on a small section, first.