Happy Hour is a moment during the bundle in which when you buy a BTA gift, you have bonus (read as free) BTA gift(s) whose numbers depend on when you ( and if you ) ALREADY purchased the bundle BEATING THE AVERAGE.
If you purchased the bundle BEATING THE AVERAGE during the 1st week, during an Happy Hour you'll be able to purchase 1 BTA gift and receive 1 + 3 BTA gifts.
If you purchased the bundle BEATING THE AVERAGE after the 1st week, you'd receive 1+2 BTA gifts bundles.
If you didn't purchase yet the bundle, you'd get 1+1 BTA gifts if you buy BTA gift during HappyHour.
Remember to check the "GIFT" checkbox when you buy during HappyHour !