Listen to Grandpa Lando, kids ... STOP DRIVING SO DARN FAST!!!
76-year-old "Star Wars" actor Billy Dee Williams -- who played Lando Calrissian in the original trilogy -- was involved in a minor car accident Tuesday in L.A..
An eyewitness tells us Williams accidentally backed into another car in a parking lot on Sunset, resulting in a vehicular love tap ... but Billy said the accident never woulda happened if the other driver wasn't so speedy.
And we're not kidding ... Billy actually used the phrase "Young people today."