Clay Aiken appeared on Tuesday night's episode of 'Watch What Happens Live' on which he had some choice words about Rihanna.

Under pressure in the show's Plead the Fifth segment, the 33 year old was asked: "What current pop singer do you think wouldn't make it past the first round of 'American Idol?'"

The 'Celebrity Apprentice' star and former 'AI' contestant thought for a minute and said there were "too many of them," and added, "I stopped listening to them because they can't sing."

Instead of pleading the fifth, Aiken answered host Andy Cohen's question with: "Rihanna has some pitch problems, for sure." Ouch.

Aiken was a guest on the half-hour show along with Jenna Jameson and Robin Byrd. He not only shared his thoughts on Rihanna, but he also played "Marry, Screw, Kill" with 'American Idol' stars Ryan Seacrest, Simon Cowell and Randy Jackson, and admitted to having minor plastic surgery.

Hey, you have to give the guy credit for not avoiding the questions and pleading the fifth. Aiken is currently on this season's 'Celebrity Apprentice,' and just released his latest album, 'Steadfast,' on March 26.

Watch Clay Aiken Diss Rihanna on 'Watch What Happens Live'