How do you get sharpie off of legos?

Spray it with aerosol hair spray, not the pump kind. This will remove permanent marker or ink from almost anything. If that does not work, and it is a plastic surface that you would be able to wipe dry erase marker off of, you can write over the sharpie with the dry erase marker, and it will usually wipe off both the dry erase marker and the permanent marker.