In a comic scene in this work, a maid disguised as a doctor produces a huge
In a comic scene in this work, a maid disguised as a doctor produces a huge magnet and pretends to cure two men, intoning "Questo e quel pezzo."  The talents of Adriana Gabrielli, who had recently become the librettist's mistress, induced its composer to write challenging skips and an astonishing range into the aria "Come scoglio."  This opera's action is spurred by a wager of one hundred sequins between the cynical Don Alfonso and the officers Ferrando and Guglielmo, who have misplaced faith in the sisters Dorabella and Fiordiligi.  FTP name this light opera with libretto by da Ponte and composed by Mozart whose title translates roughly as "Women are like that."
In a comic scene in this work, a maid disguised as a doctor produces a huge magnet and pretends to cure two men, intoning "Questo e quel pezzo."  
{Cos?fan tutte,} ossia La Scuola degli Amanti (accept Women are like that, or School for Lovers, or So Do They All, or School for Lovers, or any other reasonably close answer, before the English translation is mentioned in the question)