Singer John Mayer was forced to apologize to ex-girlfriend Jennifer Love Hewitt, after joking about his romance with the star during in impromptu comedy routine.

Mayer made a surprise appearance at The Laugh Factory in Hollywood on 26 May (06), where he talked about his relationship with the Ghost Whisperer actress.

The pair dated briefly in 2002, but Mayer said he never got to have sex with Hewitt because of a bout of food poisoning, brought on by some bad fish.

Mayer tells American publication Us Weekly, "It really was me making fun of myself."

The singer, who reportedly wrote hit Your Body is a Wonderland as a tribute to his ex, says he felt remorseful after his raunchy comedy routine and immediately sent an apology to Hewitt.

He adds, "I'm a wimp."