All you need is to dial the simple USSD Code below and 1GB will be given to you, but you won't be able to use your free 1GB immediately, the plan is only works during weekends (Saturday and Sunday).
To Get Airtel Weekend Bundle of 1GB For Free
1. Make sure you don't have any airtime on your phone to avoid deduction of your money.
2. Dial *475# twice to activate 1GB data for free
3. You will receive a pop up message like: This plan is only available on Saturday and Sunday. And when you re-dial the code, you will see another pop up message like: You have already purchased...
4. That means, your weekend bundle has activated for free! Usable only at 12am on Saturdays till Sunday 11:59am.
I myself just got the 1GB for free on two different Airtel sim cards, but unfortunately I was unable to confirm the data, whether it is browsing or not, this is because we are not yet at the weekend. Once you have got your own, just keep your sim till weekend to test it, then you can come back here and post your experience about it.