So Survey Monkey does not have the ability to generate random codes for Mechanical Turk respondents to prove they did a survey so this link will generate a nice clean random code for them to input into Turk and survey monkey.
Make the last question of your Survey Monkey Survey similar to the one below
Please click the link below and you will receive a unique code. Please copy and paste the unique code into the box below and use it as your survey code as well.