The phrase "patience, young grasshopper" is popularly associated with the 1970s TV series called "Kung Fu." The show starred David Carradine as Kwai Chang Caine, a Shaolin monk and martial artist wandering through the American Old West in search of his half-brother and spiritual enlightenment.
Throughout the series, Caine's mentor, Master Po (played by Keye Luke), often uses the phrase "patience, grasshopper" or "patience, young grasshopper" to impart wisdom and life lessons to his young student, Caine. The term "grasshopper" is a term of endearment used by the master to refer to his student.
The phrase became widely recognized and has since been referenced in various forms of popular culture, even outside the context of the original TV series. It is often used humorously to remind someone to be patient and learn from their experiences, much like a student learning from a wise teacher.