The friend could easily submit far more answers than 23 if need be. He just needs to go to the toilet. Step 1: 10 bits information - First 10 answers as second

The friend could easily submit far more answers than 23 if need be. He just needs to go to the toilet. Step 1: 10 bits information - First 10 answers as seconds from start of exam. After x seconds, friend goes to toilet. Step 2: Restart counter Step 3: On return from the toilet, take time taken in toilet. You may want to limit this to 6 bits of information / ~ 1 minute in the toilet. Anything longer might be suspicious. Step 4: Restart counter Step 5: Only 7 bits of information to hand over to get 23 questions. Count time till he leaves. Step 6: Repeat toilet-going process for more answers in different situations. There should be no suspicions, as the answer-receiver will not go to the toilet. Do not drink tea when attempting this method.