Laudator Temporis Acti

Diodorus of Sinope, The Heiress, fragment 2, lines 35-40, quoted by Athenaeus 6.239 e-f (tr. S. Douglas Olson):

When someone burps in their direction
after he eats radishes or rotten sheatfish,
they insist he's had violets and roses for lunch.
And if the host is lying on a couch with one of them
and lets a fart, the other guy leans over to sniff it and begs to be told:
"Where do you get that incense from?"

                οἷς ἐπειδὰν προσερύγῃ
ῥαφανῖδας καὶ σαπρὸν σίλουρον καταφαγών,
ἴα καὶ ῥόδα φασὶν αὐτὸν ἠριστηκέναι.
ἐπὰν δ' ἀποπάρδῃ μετά τινος κατακείμενος
τούτων, προσάγων τὴν ῥῖνα δεῖθ' αὑτῷ φράσαι·
"πόθεν τὸ θυμίαμα τοῦτο λαμβάνεις;"

This reminds me of Juvenal 3.100-108 (tr. G.G. Ramsay):

They are a nation of play-actors. If you smile, your Greek will split his sides with laughter; if he sees his friend drop a tear, he weeps, though without grieving; if you call for a bit of fire in winter-time, he puts on his cloak; if you say 'I am hot,' he breaks into a sweat. Thus we are not upon a level, he and I; he has always the best of it, being ready at any moment, by night or by day, to take his expression from another man's face, to throw up his hands and applaud if his friend gives a good belch or piddles straight, or if his golden basin make a gurgle when turned upside down.

natio comoeda est. rides, maiore cachinno
concutitur; flet, si lacrimas conspexit amici,
nec dolet; igniculum brumae si tempore poscas,
accipit endromidem; si dixeris 'aestuo,' sudat.
non sumus ergo pares: melior, qui semper et omni
nocte dieque potest aliena sumere vultum
a facie, iactare manus, laudare paratus,
si bene ructavit, si rectum minxit amicus,
si trulla inverso crepitum dedit aurea fundo.

I don't see the parallel discussed in J.D. Duff's commentary on Juvenal (1898; rpt. Cambridge: Cambridge University Press, 1929) or in Gilbert Highet's Juvenal the Satirist (1954; rpt. New York: Oxford University Press, 1961), which are the only books about Juvenal on my shelves. John E.B. Mayor's commentary, 4th ed. (London: Macmillan, 1889), available through Google Book Search, doesn't note the parallel. I do see it mentioned in N. Lemaire's 1823 edition of Juvenal. Newer commentaries, e.g. by Edward Courtney (London: Athlone, 1980) and Susanna Morton Braund (Cambridge: Cambridge University Press, 1996), are unavailable to me, as is Otto Ribbeck, Kolax: Eine ethologische Studie (Leipzig: S. Hirzel, 1883) = Abhandlungen der Philologisch-Historischen Klasse der Königl. Sächsischen Gesellschaft der Wissenschaften, Bd. 9, no. 1.

Ben Jonson, Sejanus: His Fall, Act I, Scene 1, lines 33-41, imitates Juvenal:

Laugh when their patron laughs; sweat, when he sweats;
Be hot, and cold with him; change every mood,
Habit and garb, as often as he varies;
Observe him, as his watch observes his clock;
And true, as turquoise in the dear lord's ring,
Look well, or ill with him: ready to praise
His lordship, if he spit, or but piss fair,
Have an indifferent stool, or break wind well,
Nothing can scape their catch.

Cf. also Karl Marx, letter to Friedrich Engels (Nov. 19, 1859 = Werke XXIX, 513), quoted by S.S. Prawer, Karl Marx and World Literature (Oxford: Clarendon Press, 1976), p. 199:

This fellow finds it natural to hear cries of 'Hurrah' when he has broken wind.

"This fellow" is Ferdinand Freiligrath.