Adam Lambert can't think of anything nice to say about Clay Aiken -- so he says nothing at all.
The American Idol season eight runner-up took a swipe at the season-two runner-up Thursday night during a guest appearance on Bravo's Watch What Happens, smirking at the mere mention of Aiken's name.
Per show tradition, host Andy Cohen asked Lambert play along with "Plead the Fifth," a regular segment where Cohen asks provocative questions of his panelists, for which they have the option to "plead the fifth" on all but one.
"Say three nice things about Clay Aiken." he requested of Lambert, whose raised-eyebrow reaction drew laughs from the studio audience.
"Can't think of any," he responded, to which Cohen asked: "Want to plead fifth?"
"No, I just can't think of any nice things," said Lambert, laughing.
Besides being runners-up on the Fox competition, Lambert and Aiken also share a penchant for candor -- and, apparently, bad blood on either side. In 2009, Aiken launched a bitter 2009 tirade against Lambert, one of whose TV performances he slammed as "awful," "contrived" and "slightly frightening."
Earlier this week, Lambert's second album, Trespassing, debuted at No. 1 on the Billboard 200, besting the likes of Adele, Carrie Underwood and Norah Jones. The record was released on May 15, moving 77,181 copies in its first week out, according to Nielsen SoundScan.
As for Aiken, he returned to reality TV this spring for NBC's Celebrity Apprentice, making it to the top two: he battles Arsenio Hall in Sunday's finale, presided over by Donald Trump.
Watch Lambert's Watch What Happens segment below.