Ketubot, Chapter One, Mishnah Seven
This mishnah contains another debate between a man and woman over the circumstances in which she lost her physical signs of virginity.
She says, I was struck by a piece of wood,
And he says, No, you, rather you have been trampled by a man
Rabban gamaliel and Rabbi Eliezer say: she is believed,
And Rabbi Joshua says: We do not live by her mouth, rather she is in the presumption of having been trampled by a man, until she brings proof for her statement.
In this case, when the husband comes to court claiming that his wife was not a virgin, the woman responds that she did not lose her physical signs of virginity through sexual intercourse but rather by being struck by a piece of wood, meaning she lost her hymen in some other way. According to Rabbi Meir (see mishnah three) if the court believes her, she would receive a full ketubah of 200. According to the Sages she receives a ketubah of 100. In any case, she is claiming that she does receive some ketubah.
The man responds that she lost her virginity by having engaged in sexual intercourse. The phrase trampled by a man is an illustrative means of saying that she had sex with a man and not that she lost her virginity from a stick. Assumedly his goal is to not pay her any ketubah.
Again Rabban Gamaliel and Rabbi Eliezer rule in her favor. The same reason which I offered in yesterdays mishnah applies here: since she is certain and he is uncertain, she is believed.
Similarly, Rabbi Joshua holds that she is not believed, and that the money remains with the husband. Again, the same reason as in yesterdays mishnah applies: in order for her to extract money she must provide proof.