What better way to spend your birthday than with David Letterman! Birthday girl Paris Hilton stopped by the Late Show to chat about her "amazing relationship" with Cy Waits, growing her empire and her plans to have kids.

She tells Dave, "I think having kids is the meaning of life."

The 30-year-old heiress was also there to promote the Paris App for iPhones in which the user can snap a picture of themselves ... and Paris appears in the shot. After the host gets his picture taken, he takes a few jabs at Paris' beau Cy Waits who was just off-camera.

Letterman says to Paris, "I wonder what the boyfriend thinks of this shot. Mr. Big Shot back there in his Members Only jacket." Speaking of Cy, check out this sexy smooch outside of Letterman's studios. Get a room!

paris hilton dress kissing jacket denim

Find out what question made Paris blush ... after the jump.