Roll out prepared cookie dough 1/8 in. thick and cut out with gingerbread boy cutter from set. Bake and cool.
Prepare color flow icing according to package instructions. Tint portions green, red, black and reserve some white. Use tip 3 and parchment bag filled with full-strength white icing to outline cookie and pipe hair.
Use tip 2 and full-strength green icing to outline outfit. Use tip 3 and thinned green color flow icing to fill in outfit. Let dry.
Pipe eyes with tip 3 and full-strength black icing. Use tip 2 and full-strength red icing to outline mouth. Use tip 2 and full-strength white icing to pipe reflection in eyes. Use tip 3 and full-strength red icing to pipe buttons. Pipe accent on buttons with tip 2 full-strength and white icing.