Singer Adam Lambert can't think of anything nice to say about Clay Aiken.

Lambert appeared Thursday night on cabler Bravo's Watch What Happens, where host Andy Cohen asked him to play along with Plead the Fifth, a regular show segment where guests are asked provocative questions and can “plead the fifth” on all but one.

The American Idol season eight runner-up decided to keep quiet when asked about Aiken, the season two runner-up.

“Say three nice things about Clay Aiken,” Cohen asked Lambert.

“Can't think of any,” Lambert said with a smirk.

“Want to plead the fifth?”

“No, I just can't think of any nice things,” Lambert answered with a laugh. (Watch the entire segment at

Lambert's sophomore album Trespassing debuted at Number One on Billboard's album chart, making him the first openly gay male artist and the seventh American Idol finalist to climb to the top spot on the chart.

Aiken returned to television this spring, competing on NBC's Celebrity Apprentice. On Sunday's finale, Aiken came in second behind late-night talk show host Arsenio Hall.