In a deep skillet, heat 1 1/2 inches of oil over medium heat.
While the oil is heating, make the batter: In a wide mixing bowl, combine 2 cups of the pancake mix, the water and 6 teaspoons of hot sauce. Place the remaining 1/2 cup of pancake mix in another wide mixing bowl. Arrange the batter and the bowl of pancake mix near the stove. Line a plate with a few paper towels and keep within reach.
Once the oil is heated, toss the chicken pieces with the remaining 2 teaspoons of hot sauce, then toss them in the dry pancake mix, coat evenly and shake off the excess. (The dry pancake mix will help the batter stick to the chicken pieces.) Add some of the chicken to the batter (youre going to batter and fry in 3 to 4 batches) and toss with your fingers or a fork. Remove the first batch from the batter, shaking off the excess, and carefully add the chicken to the hot oil. Fry the chicken for 2 minutes on each side, flipping once, until deep golden brown. Remove the fried chicken from the oil and drain on the paper towellined plate, then season with salt. Repeat until all the popcorn chicken bites are fried.
Stir the chopped scallions and pepper into the blue cheese dressing. Serve the chicken immediately with the dressing on the side. Garnish the platter with the celery sticks.