Laudator Temporis Acti

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 = Ferdinand Freiligrath. I no longer have access to Prawer's book, so I don't know if he connected this with a famous passage of Juvenal describing a toady (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.

See especially lines 106-107.