Use a heavy-bottomed 4-quart saucepan with fitting lid (do not use a nonstick pot or Dutch oven).
Due to the retention of heat in the pot, you must transfer the popcorn immediately; otherwise, the popcorn will caramelize and burn.
Place the oil and 3 popcorn kernels in an uncovered 4-quart saucepan over medium-high heat. Once the kernels pop, add the remaining ½ cup kernels, salt, and sugar. Give the pot a good quick shake, then cover with the lid.
As the popcorn starts to pop, pick up the pot and give it a quick shake every few seconds until the popcorn is halfway popped, about 2 minutes. With caution, carefully lift the lid just enough to pour in the wheat germ. Immediately close the lid and shake the pot to evenly distribute the wheat germ. Continue to pop until the popping slows down, 1 to 2 more minutes. Immediately remove from the heat and pour into a large serving bowl.