Robby is a BMX bicycle stunt rider.
In "Son of Stan" he appears when Stan and Francine race to see who will take care of Steve. After winning his race, he gets the girl and the admiration of his 1980s vintage friends. After Stan wipes out on his bicycle, he stops to tell that he is from the big city while doing wheelie stands.
He is a courier the hospital uses to test to see if Stan is actually Hayley's father and a match for her kidney in "The Kidney Stays in the Picture". Due to Stan's poor insurance, the hospital refuses to pay for the tests to be overnighted to the lab so they rely on Robbie. When Robbie returns from the trip, he notes that he discovered that his live-in girlfriend is also a prostitute.
Robby beats Steve at chess in "Spelling Bee My Baby".