A Tokyo cab driver has been arrested for allegedly feeding his female passengers snacks laced with diuretics so he could satisfy his fetish for seeing them lose control and urinate on his back seat.

"I got excited by watching women trying to withstand the urge to urinate," 41-year-old Toshihiko Nishi told investigators.

Police searched Nishi's computer and found a collection of security videos showing 50 different women peeing themselves in his cab. He allegedly lured the women into long trips by offering half-price fares, and then offered them crackers laced with diuretics.

One woman said that when she told him she needed a toilet, he refused to let her out, instead passing her an absorbent sheet and telling her to urinate on that.

Nishi admitted to police that he "bought diuretics through the Internet, and crushed them to mix with crackers."

He's being investigated for "committing a violent act."

[Photo: Getty Images]