Here is a great easy prank to play on a friend at the beach.
1. Dig a deep hole in the sand
2. Place a blanket over the entire hole to hide it
3. Have 2 friends sit on the opposite sides of the blanket
4. Have someone with a camera recording nearby or set one up
4. Invite someone to join you in the middle
Note: Safety is always number 1. Make sure the person you are playing the prank on does not have any health issues.