I don't think Caesar was a hippie, but like a lot of young folk in history, did do things in dress and deportment to annoy the older generations.
A Companion to Julius Caesar (Google Books Link) summarizes a lot of the various controversies over Caesar and his tunic. The ultimate sources are Suetonius, Lives of the 12 Caesars and several cracks by Cicero in his letters.
"Beware the badly belted boy, " Sulla is supposed to have warned about Caesar (Suetonius, Lives of the 12 Caesars). According to Suetonius, Caesar always used to wear a belt over a senatorial tunic with its broad stripe, which in his case had fringed sleeves which reached down to his wrists.
Caesar clearly was something of a man of fashion, but he was not unusual in this, and the charges leveled against him in this regard were used against many of his contemporaries. It was no accident that one of his leading political opponents, Cato the Younger, went out of his way to represent himself as the rough, hairy Roman of tradition with his short toga, which he wore in the old-fashioned way without a tunic underneath (Plutarch, Cato Minor)
The fact that the tunic still rankled with Cicero some 20 years later and was reported by Suetonius about 150 years after that surely shows that Caesar made an impression that lasted.