Natalie Zemon Davis, "The Rites of Violence: Religious Riot in Sixteenth-Century France,"
Past & Present
, No. 59 (May, 1973) 51-91 (at p. 89, n. 121):
The most interesting new youth group formed in this period was, however,
the Whistlers or Sifflars of Poitiers, so-called from a whistle the members wore
around their necks. Founded among students around 1561, it initially mocked
both religions. Initiates had to swear by flesh, belly, death and "the worthy
double head, stuffed with Relics" and by all the Divinity in this pint of wine,
that they would be devoted Whistlers, and that instead of going to Protestant
service, mass or Vespers, they would go twice a day to a brothel, etc. The
group grew to some sixty-four youths and became especially hostile to the
Reformed Church and its services, perhaps because of Reformed hostility to
them. Its members began to go around armed. Hist. eccl., i, pp. 844-5.
The reference is to Histoire ecclésiastique des églises réformées au royaume de France
, edd. G. Baum and E. Cunitz, 3 vols. (Paris, 1883-1889).