This whole link has some pretty funny things in it . . .

In Horace (Satires 1.8.37), a talking statue of Priapus says:
mentior at sīquid, merdīs caput inquiner albīs
corvōrum atque in me veniat mictum atque cacātum
Iūlius, et fragilis Pediātia, fūrque Vorānus.
("But if I'm telling a lie, may my head be spattered with the white droppings
of ravens, and may Julius, delicate Pediatia, and the thief Voranus
come to piss and shit on me!" )
In one of his verse fables (4.18.25), Phaedrus speaks of some dogs who, on hearing thunder,
repente odōrem mixtum cum merdīs cacant
("suddenly they shit out a stink mixed with turds" )
The word can also be used in a metaphorical sense, as at Martial 3.17, speaking of a tart which had been blown on by a man with impure breath (caused no doubt by oral sex) to cool it down:[96]
Sed nēmō potuit tangere: merda fuit.
("But nobody could touch it: it was a piece of shit." )