quid est: an appeal of impatient indignation, cf. Pl. Amph. 556 “quid est? quo modo? … tibi … linguam abscidam.”
quid moraris emori: i.e. what pleasure can you take in life when such disgraceful things are possible? cf. Hor. Carm. 3.27.58 “quid mori cessas?” Ov. Her. 9.146 “impia quia dubitas Deianira mori?”
[2] sella in curuli: apparently indicating that Nonius had just attained the first of the curule offices, the curule aedileship, perhaps as part of the program settled upon at the conference at Luca in 56 B.C. This would very well fit Nonius Asprenas, who was an officer of Caesar in the African War in 46 with the title of proconsul (Bell. Afr. 80.4; Bell. Hisp. 10.2), and perhaps not so well M. Nonius Sufenas, who so late as 56 was only tribunus plebis.
[2] struma: a scrofulous tumor, used here as an uncomplimentary nickname, from the manner in which rascals were attachmg themselves to the high offices of the state; cf. Cic. Sest. 65.135 “strumam civitatis” ; Plin. NH 37.81 “Nonius senator, filius ‘strumae Noni’ eius quem Catullus poeta in sella curuli visum indigne tulit” , where the reproduction of the order of the words in Catullus seems to indicate that Pliny understood Struma to be an epithet and not a true cognomen.
[3] perierat: παρὰ προσδοκίαν, for iurat.
[3] Vatinius: in the year 55 the Caesarians succeeded in electing Vatinius praetor over Cato. Already in 56 Cicero had charged him with impudent assurance regarding a future consulship, and to the same characteristic Catullus refers here. But the coveted advancement was doubtless promised by Caesar at Luca, and this promotion to the praetorship was regarded but as a step thereto by Vatinius and by Catullus as well, whose indignation was all the more fired by it.
[4] The first verse is identical with the last also in Catul. 16.1ff. and Catul. 36.1ff.