The Andy Griffith Show (1960)

S7E14 Goober Makes History

Frustrated by being the least informed person in Mayberry, Goober decides to take a break and heads out for a fishing trip. During his time away, he unexpectedly grows a beard, which leads him to think he's gained wisdom. With this newfound confidence, he becomes insufferably dull, lecturing everyone around him and driving the townsfolk to their wits' end.