Sprint offers a $25 Gift Card to all new contracts and those who referred them. It's very very simple, all you need to do is call #733 from your new Sprint line and enter your referral's phone number to the IVR. No need to talk to customer service or another human.
You can use any friend or other family member's number, so both of you get a gift card each. If you don't know anyone on Sprint, PM me and I'll be happy to share my number as a referral. Step by step guide here:
1. Call #733 from your new Sprint line.
2. Press 1 for English.
3. Press 2 to continue.
4. Enter referral#
when prompted to enter a referrer.
5. Confirm referral and say goodbye to the machine.
6. Anxiously wait for your $25 gift card to arrive in the mail in 6-8 weeks.
* You must do this within 15 days of activation.
* Upgrades and/or line additions to family plans are not eligible for this offer.
* Contract renewals and extensions are not eligible.
* You cannot refer yourself, i.e. the the referring line must be under a different name.
Here's the program page: Sprint Referral Program