If you decide you do not want to challenge, say "okay" and the game continues. If you decide to challenge, call "challenge" and then neutralize the clock. No tiles may be drawn during a challenge. Challenges may not be taken back unless you misunderstood the designation of a blank tile. The club director or other designated person will verify the play using the official word list. If any word you challenge is judged unacceptable, your opponent returns the tiles played to his rack and then starts your clock, losing his turn and scoring zero for that play. If all of the words you challenge are ruled acceptable, you lose your turn (scoring zero), and you may start your opponent's clock.
Newcomers will be allowed free challenges during their first club visit. This means that if you challenge unsuccessfully, you will not lose your turn. In this case, your clock is started instead of your opponent's and you may play your turn as if you did not challenge. Also, if your play is challenged and ruled unacceptable, you will be allowed to make a different play without penalty.