Macrobius, Saturnalia 2.1:
“Who is there, that has taken care to read those those books of his jokes which his freedman composed, who does not know how much Cicero excelled in humor? (Though, some suspect that the freedman was the author.) Who is there, who doesn’t know that he was often called the ‘consular clown’ by his enemies? Vatinius mentioned this in his own speech. I would, if it wouldn’t take too long, recall those cases in which he represented guilty clients, which he won by joking.”
Cicero autem quantum in ea re valuerit quis ignorat qui vel liberti eius libros quos is de iocis patroni conposuit, quos quidam ipsius putant esse, legere curavit? Quis item nescit consularem eum scurram ab inimicis appellari solitum? quod in oratione etiam sua Vatinius posuit. Atque ego, ni longum esset, referrem, in quibus causis, cum nocentissimos reos tueretur, victoriam iocis adeptus sit.