In Iceland, according to Margarethe Filhés (as quoted by Max Bartels, Zeitschrift für Ethnologie, 1900, ht. 2-3, p. 57), it may be known whether a youth is pure or a maid is intact by their susceptibility to tickling. It is considered a bad sign if that is lost.
I am indebted to a medical correspondent for the following communication: "Married women have told me that they find that after marriage they are not ticklish under the arms or on the breasts, though before marriage any tickling or touching in these regions, especially by a man, would make them jump or get hysterical or 'queer,' as they call it. Before coitus the sexual energy seems to be dissipated along all the nerve-channels and especially along the secondary sexual routes,—the breasts, nape of neck, eyebrows, lips, cheeks, armpits, and hair thereon, etc.,—but after marriage the surplus energy is diverted from these secondary channels, and response to tickling is diminished. I have often noted in insane cases, especially mania in adolescent girls, that they are excessively ticklish. Again, in ordinary routine practice I have observed that, though married women show no ticklishness during auscultation and percussion of the chest, this is by no means always so in young girls. Perhaps ticklishness in virgins is Nature's self-protection against rape and sexual advances, and the young girl instinctively wishing to hide the armpits, breasts, and other ticklish regions, tucks herself up to prevent these parts being touched. The married woman, being in love with a man, does not shut up these parts, as she reciprocates the advances that he makes; she no longer requires ticklishness as a protection against sexual aggression."
Alrutz's views are summarized in Psychological Review, Sept., 1901.
Die Spiele der Menschen, 1899, p. 206.