10) Give the "I'll follow you" signal and then go the opposite direction.

9) Send him back to the boat for more air.

8) Tell him to meet you at the "anchor line" on a drift dive.

7) Two words: camouflage wetsuit.

6) Tell him you spent a lot of money for this dive and you want to get the maximum bottom time possible. So the plan is for one person to breathe all his gas, share air with his buddy, then do an emergency ascent from 130 feet.

5) Let him enter the shipwreck first, then close and lock the door.

4) While gearing up, tell him not to pay attention to the large sores on your mouth. If he needs air, you'll be there.

3) Blow up party balloons on the boat using his regulator.

2) Paint "FULL" needles on his gauges and remove the real ones.

1) Confess you never really got certified, you're just using a c-card you found while snorkeling.