It's basically a referral code. Refer people to use your orange key, and you will receive a bonus each time someone uses your key. That person will also get their own bonus! If you're new to ING and thinking of creating an account with them, be kind and use my orange key: 35561445S1
Once your account is set-up with ING, you will get your own orange key, and can start referring others to start using it! You each get $25! You can refer up to 50 people.