Most Iconic Cameos in Blockbuster Movies

Neil Patrick Harris in Harold and Kumar Go to White Castle

The former “Doogie Howser, M.D.” star made a totally unexpected appearance in the 2004 stoner comedy, which essentially paved the way for his subsequent role in “How I Met Your Mother”.

His straight-edge image was erased with this cameo as he played an ecstasy-fueled hitchhiker, picked up en route to the fast food restaurant, and gives many references to drugs and crass talk about women.

Neil Patrick Harris in Harold and Kumar Go to White Castle

This was the type of character they were looking for when casting for Barney Stinson, so the well-received cameo has been credited with leading him to that famous role.