Add the vegetable oil and 3–4 popcorn kernels to a large, heavy-bottomed pot. Cover and heat over medium-high heat until the test kernels pop.
Add the remaining popcorn kernels and shake the pot to coat them in the oil. Add the sugar and salt, then shake again to evenly coat the kernels.
Cover the pot and cook, shaking constantly to prevent the popcorn and sugar from burning.
Continue cooking until the popping slows to about 2 seconds between pops. Immediately remove the pot from the heat and pour the popcorn into a large serving bowl.
Remove any unpopped kernels.
Serve warm and enjoy.
Notes
You can store the leftovers at room temperature in an airtight container for up to 3-4 days.