Lohan & Hilton: From Kinky to Kinko's

La Lohan climbed the ranks of the kink scale when she bought a pair of sexy diamond encrusted handcuffs at Fred Segal in Beverly Hills on Sunday ... for a blingin' $820! To prevent them from getting wrapped around the wrong wrists, Lindsay wore the key on a gold chain. How convenient!

Meanwhile, paparazzi magnet Paris Hilton spent part of her Sunday in a cryptic hangout for an heiress: Kinko's copy shop. Paris spent an hour making copies and playing around on one of the computers. What could be so important that she just had to take care of it herself? Britney's 25th birthday is only a week away ... maybe she's making party invites?