Question: Who sings what condition my condition is in?
Disambiguated questions and answers: question: What group sings Just Dropped In (To See What Condition My Condition Was In)?
Who sings lead on Just Dropped In (To See What Condition My Condition Was In)?
answer: Kenny Rogers and the First Edition
Kenny Rogers
Natural Questions answer: Jerry Lee Lewis
Mickey Newbury (from the Wikipedia article "Just Dropped In (To See What Condition My Condition Was In)")