So he decided to give them a polygraph test.
With Kimmel's parking lot security guard/sidekick Guillermo acting as witness, Lowe and Giudici underwent a test administered by polygraph expert Dennis Blackstock.
Kimmel revealed the results on his show Monday night, and – to the host's surprise as much as anybody's – Blackstock stated that he had definitive results from the test, and that those results confirmed Lowe and Giudici's claims: The pair didn't sleep together until they were married, waiting 16 months. (Click here for PEOPLE's wedding coverage.)
"I'm proud and disappointed at the same time," Kimmel said.